Kuldev Singh, MD

All Publications

• Novel Parameter of Corneal Biomechanics That Differentiate Normals From Glaucoma JOURNAL OF GLAUCOMA Lee, R., Chang, R. T., Wong, I. Y., Lai, J. S., Lee, J. W., Singh, K. 2016; 25 (6): E603-E609

  Abstract

  To identify novel corneal biomechanical parameters differentiating glaucomatous from normal eyes.Sixty subjects with varying degrees of glaucoma severity and 61 normal controls underwent corneal biomechanical measurements including corneal deformation amplitude, inward and outward applanation length and velocity, and highest concavity time in 1 eye per subject at Queen Mary Hospital, Hong Kong. Measurements were taken with the Corvis ST device, a noncontact tonometer coupled with a high-speed Scheimpflug camera. The intraocular pressure (IOP) and central corneal thickness (CCT) were also measured.Significant findings included differences in outward applanation velocity (glaucoma: -0.37±0.01 m/s; control: -0.32±0.01 m/s; P=0.001), peak distance (glaucoma: 2.37±0.03 mm; control: 2.30±0.02 mm; P=0.005), and highest concavity time (glaucoma: 16.75±0.08 ms; control: 17.05±0.07 ms; P=0.002) between the 2 groups, after correcting for IOP, CCT, and age. Both outward applanation velocity and peak distance were moderately correlated with IOP and CCT. However, highest concavity time was not correlated with either IOP or CCT (R=0.0140 and 0.000055, respectively). Age was not correlated with any of the 3 parameters.Glaucomatous eyes have a greater mean outward applanation velocity and peak distance, but shorter time to highest concavity than eyes without glaucoma. The difference in time to highest concavity does not correlate with age, IOP, or CCT, suggesting that this parameter may be a marker of increased pressure susceptibility that is independently associated with glaucoma risk.

  View details for DOI 10.1097/IJG.0000000000000284

  View details for Web of Science ID 000379584800007

  View details for PubMedID 26035421

• Oral Contraceptive Use and Prevalence of Self-Reported Glaucoma or Ocular Hypertension in the United States OPHTHALMOLOGY Wang, Y. E., Kakigi, C., Barbosa, D., Porco, T., Chen, R., Wang, S., Li, Y., Singh, K., Pasquale, L. R., Lin, S. C. 2016; 123 (4): 729-736

  View details for DOI 10.1016/j.ophtha.2015.11.029

  View details for Web of Science ID 000372718300016

• Effectiveness of Glaucoma Counseling on Rates of Follow-up and Glaucoma Knowledge in a South Indian Population AMERICAN JOURNAL OF OPHTHALMOLOGY Do, A. T., Pillai, M. R., Balakrishnan, V., Chang, R. T., Robin, A. L., Singh, K., Lee, B. W. 2016; 163: 180-189

  Abstract

  To evaluate the impact of traditional counseling and patient-centered counseling, either alone or with recorded audio counseling reinforcement, on glaucoma knowledge and clinical follow-up.Prospective randomized controlled trial.Newly diagnosed adult glaucoma patients were randomized to one of three categories of glaucoma counseling: traditional counseling, patient-centered counseling, or patient-centered counseling with audio counseling reinforcement. Demographic and clinical information from each subject was ascertained, and all subjects completed the Glaucoma Knowledge Assessment before and after counseling sessions at the time of diagnosis and at one-month follow-up. Patients were instructed to return to clinic for routine follow-up at 1, 3, 6, 9, and 12 months after enrollment. A multivariate logistic regression model was utilized to determine factors associated with appropriate clinical follow-up.Overall, only 13.5% of subjects had appropriate clinical follow-up at one year, defined as attending at least three follow up visits during that interval, and there was no significant difference between counseling groups. The mean Glaucoma Knowledge Assessment Score (GKAS) improved by 77.6% with the initial counseling intervention (p<0.0001), decreased by 17.4% within a one-month period following initial counseling, and improved by 22.8% (p<0.001) after the second counseling intervention. Monthly household income over 2500 rupees, (GKAS) greater than 5 after initial counseling, and undergoing any ocular surgical procedure were all independent predictors of appropriate follow-up.While all three counseling methods resulted in transient improvement of patient knowledge regarding glaucomatous disease, follow-up rates were poor for all groups. Poor retention of glaucoma knowledge may impact the likelihood of patient follow up, and reinforcement with repeated counseling may be beneficial with regard to both disease knowledge and follow-up.

  View details for DOI 10.1016/j.ajo.2015.12.009

  View details for Web of Science ID 000371447500024

  View details for PubMedID 26705095

• Assessment of corneal biomechanical parameters in myopes and emmetropes using the Corvis ST CLINICAL AND EXPERIMENTAL OPTOMETRY Lee, R., Chang, R. T., Wong, I. Y., Lai, J. S., Lee, J. W., Singh, K. 2016; 99 (2): 157-162

  Abstract

  Prior studies have demonstrated conflicting results regarding the relationship between corneal biomechanical properties and refractive error. Thus, the purpose of this study was to compare the corneal biomechanical parameters of myopes and emmetropes.Ninety-four subjects with varying degrees of myopia (aged 29 to 74 years, spherical equivalent [SE] -0.5 to -17.5 D) and 25 emmetropes (aged 19 to 75 years, SE: -0.5 to +0.5 D) presenting at the Queen Mary Hospital, Hong Kong were recruited sequentially for this prospective study. All patients were phakic with no history of coexisting ocular disease. The corneal biomechanical parameters of the right eye of each subject were analysed using the Corvis ST non-contact tonometer. Intraocular pressure (IOP) was measured using both the Corvis ST and the Topcon Non-Contact Tonometer CT-80. Refractive error was measured by non-cycloplegic subjective and objective refractometry.High myopes (SE greater than -6.00 D) demonstrated greater mean outward applanation velocities (p < 0.001) and peak distance measurements (p = 0.009) compared to both low to moderate myopes (SE -0.50 to -6.00 D) and emmetropes. Both outward applanation velocity and peak distance were moderately correlated with refractive error (p ≤ 0.001), strongly correlated with IOP and weakly correlated with central corneal thickness. There were no statistically significant differences in age, IOP or central corneal thickness among emmetropes, low to moderate myopes or high myopes.Within this study of Chinese subjects, high myopes demonstrate greater corneal mean outward applanation velocity on Corvis ST testing, than emmetropes. In particular, those with high myopia (SE greater than -6.00 D) show a distinct corneal biomechanical profile relative to those with either emmetropia or low to moderate myopia using the Corvis ST.

  View details for DOI 10.1111/cxo.12341

  View details for Web of Science ID 000373392400010

  View details for PubMedID 26893029

• Refractive Error and the Risk of Age-Related Macular Degeneration in the South Korean Population. Asia-Pacific journal of ophthalmology (Philadelphia, Pa.) Lin, S., Singh, K., Chao, D. L., Lin, S. C. 2016; 5 (2): 115-121

  Abstract

  We investigated the association between refractive error and the prevalence of age-related macular degeneration (AMD) in a population-based study.This was a cross-sectional study.Right eyes were included from 14,067 participants aged 40 years and older with gradable fundus photographs and refraction data from the fourth and the fifth Korea National Health and Nutrition Examination Survey 2008 to 2011. Early and late AMD was graded based on the International Age-Related Maculopathy Epidemiological Study Group grading system. Autorefraction data were collected to calculate spherical equivalent refraction in diopters (D) and classified into 4 groups: hyperopia (≥1.0 D), emmetropia (-0.99 to 0.99 D), mild myopia (-1.0 to -2.99 D), and moderate to high myopia (≤-3.0 D).After adjustment for potential confounders, each diopter increase in spherical equivalent was associated with a 16% [odds ratio (OR), 1.16; 95% confidence interval (CI), 1.08-1.25] and 18% (OR, 1.18; 95% CI, 1.10-1.27) increased risk of any (early + late) and early AMD, respectively. Mild and moderate to high myopia were associated with lower odds of any and early AMD compared with hyperopia (any AMD: OR, 0.62; 95% CI, 0.4-0.95 for mild myopia; OR, 0.41; 95% CI, 0.21-0.81 for moderate to high myopia; early AMD: OR, 0.63; 95% CI, 0.4-0.99 for mild myopia; OR, 0.36; 95% CI, 0.16-0.77 for moderate to high myopia group). There was no association between refractive status and the likelihood of late AMD (P = 0.91).Myopia is associated with lower odds of any and early AMD, but not with late AMD in the South Korean population.

  View details for DOI 10.1097/APO.0000000000000169

  View details for PubMedID 26914445

• Factors Associated with Patient Press Ganey Satisfaction Scores for Ophthalmology Patients OPHTHALMOLOGY Long, C., Tsay, E. L., Jacobo, S. A., Popat, R., Singh, K., Chang, R. T. 2016; 123 (2): 242-247

  View details for DOI 10.1016/j.ophtha.2015.09.044

  View details for Web of Science ID 000368362200014

• Genome-wide association analysis identifies TXNRD2, ATXN2 and FOXC1 as susceptibility loci for primary open-angle glaucoma NATURE GENETICS Bailey, J. N., Loomis, S. J., Kang, J. H., Allingham, R. R., Gharahkhani, P., Khor, C. C., Burdon, K. P., Aschard, H., Chasman, D. I., Igo, R. P., Hysi, P. G., Glastonbury, C. A., Ashley-Koch, A., Brilliant, M., Brown, A. A., Budenz, D. L., Buil, A., Cheng, C., Choi, H., Christen, W. G., Curhan, G., De Vivo, I., Fingert, J. H., Foster, P. J., Fuchs, C., Gaasterland, D., Gaasterland, T., Hewitt, A. W., Hu, F., Hunter, D. J., Khawaja, A. P., Lee, R. K., Li, Z., Lichter, P. R., Mackey, D. A., McGuffin, P., Mitchell, P., Moroi, S. E., Perera, S. A., Pepper, K. W., Qi, Q., Realini, T., Richards, J. E., Ridker, P. M., Rimm, E., Ritch, R., Ritchie, M., Schuman, J. S., Scott, W. K., Singh, K., Sit, A. J., Song, Y. E., Tamimi, R. M., Topouzis, F., Viswanathan, A. C., Verma, S. S., Vollrath, D., Wang, J. J., Weisschuh, N., Wissinger, B., Wollstein, G., Wong, T. Y., Yaspan, B. L., Zack, D. J., Zhang, K., Weinreb, R. N., Pericak-Vance, M. A., Small, K., Hammond, C. J., Aung, T., Liu, Y., Vithana, E. N., Macgregor, S., Craig, J. E., Kraftl, P., Howell, G., Hauser, M. A., Pasguale, L. R., Haines, J. L., Wiggs, J. L. 2016; 48 (2): 189-194

  Abstract

  Primary open-angle glaucoma (POAG) is a leading cause of blindness worldwide. To identify new susceptibility loci, we performed meta-analysis on genome-wide association study (GWAS) results from eight independent studies from the United States (3,853 cases and 33,480 controls) and investigated the most significantly associated SNPs in two Australian studies (1,252 cases and 2,592 controls), three European studies (875 cases and 4,107 controls) and a Singaporean Chinese study (1,037 cases and 2,543 controls). A meta-analysis of the top SNPs identified three new associated loci: rs35934224[T] in TXNRD2 (odds ratio (OR) = 0.78, P = 4.05 × 10(-11)) encoding a mitochondrial protein required for redox homeostasis; rs7137828[T] in ATXN2 (OR = 1.17, P = 8.73 × 10(-10)); and rs2745572[A] upstream of FOXC1 (OR = 1.17, P = 1.76 × 10(-10)). Using RT-PCR and immunohistochemistry, we show TXNRD2 and ATXN2 expression in retinal ganglion cells and the optic nerve head. These results identify new pathways underlying POAG susceptibility and suggest new targets for preventative therapies.

  View details for DOI 10.1038/ng.3482

  View details for Web of Science ID 000369043900017

  View details for PubMedID 26752265

• Initial Clinical Experience With the CyPass Micro-Stent: Safety and Surgical Outcomes of a Novel Supraciliary Microstent. Journal of glaucoma Hoeh, H., Vold, S. D., Ahmed, I. K., Anton, A., Rau, M., Singh, K., Chang, D. F., Shingleton, B. J., Ianchulev, T. 2016; 25 (1): 106-112

  Abstract

  To evaluate safety and clinical outcomes of a novel supraciliary device, the CyPass Micro-Stent, for surgical treatment of open-angle glaucoma when implanted in conjunction with cataract surgery.Subjects (n=142) with open-angle glaucoma and cataract underwent combined phacoemulsification, with intraocular lens insertion, and microstent implantation into the supraciliary space of study eyes (n=167). Two analysis cohorts were prespecified based upon medicated baseline intraocular pressure (IOP): ≥21 mm Hg (cohort 1, n=65) or <21 mm Hg (cohort 2, n=102). Glaucoma medications were discontinued or tapered at surgery, and restarted at investigator discretion. The main postoperative outcome measures were adverse events, IOP changes, and number of IOP-lowering medications.Mean±SD follow-up was 294±121 days. No major intraoperative or postoperative complications occurred. Preoperative baseline mean IOP was 20.2±6.0 mm Hg and mean number of IOP-lowering medications was 2.0±1.1. Cohort 1 showed a 35% decrease in mean IOP and a 49% reduction in mean glaucoma medication usage; cohort 2 demonstrated a 75% reduction in mean medication usage while maintaining mean IOP<21 mm Hg. For all eyes, mean IOP at 12 months was 15.9±3.1 mm Hg (14% reduction from baseline). Early and late postoperative IOP elevation occurred in 1.2% and 1.8% of eyes, respectively. Two subjects developed mild transient hyphema, and none exhibited prolonged inflammation, persistent hypotony, or hypotony maculopathy.CyPass Micro-Stent implantation, combined with cataract surgery, resulted in minimal complications and reduced IOP and IOP-lowering medication use at 12 months postoperatively.

  View details for DOI 10.1097/IJG.0000000000000134

  View details for PubMedID 25304276

• Special Commentary: Supporting Innovation for Safe and Effective Minimally Invasive Glaucoma Surgery: Summary of a Joint Meeting of the American Glaucoma Society and the Food and Drug Administration, Washington, DC, February 26, 2014. Ophthalmology Caprioli, J., Kim, J. H., Friedman, D. S., Kiang, T., Moster, M. R., Parrish, R. K., Rorer, E. M., Samuelson, T., Tarver, M. E., Singh, K., Eydelman, M. B. 2015; 122 (9): 1795-1801

  View details for DOI 10.1016/j.ophtha.2015.02.029

  View details for PubMedID 25881513

• The Effect of Phacoemulsification on Intraocular Pressure in Glaucoma Patients A Report by the American Academy of Ophthalmology OPHTHALMOLOGY Chen, P. P., Lin, S. C., Junk, A. K., Radhakrishnan, S., Singh, K., Chen, T. C. 2015; 122 (7): 1294-1307

  Abstract

  To examine effects of phacoemulsification on longer-term intraocular pressure (IOP) in patients with medically treated primary open-angle glaucoma (POAG; including normal-tension glaucoma), pseudoexfoliation glaucoma (PXG), or primary angle-closure glaucoma (PACG), without prior or concurrent incisional glaucoma surgery.PubMed and Cochrane database searches, last conducted in December 2014, yielded 541 unique citations. Panel members reviewed titles and abstracts and selected 86 for further review. The panel reviewed these articles and identified 32 studies meeting the inclusion criteria, for which the panel methodologist assigned a level of evidence based on standardized grading adopted by the American Academy of Ophthalmology. One, 15, and 16 studies were rated as providing level I, II, and III evidence, respectively.All follow-up, IOP, and medication data listed are weighted means. In general, the studies reported on patients using few glaucoma medications (1.5-1.9 before surgery among the different diagnoses). For POAG, 9 studies (total, 461 patients; follow-up, 17 months) showed that phacoemulsification reduced IOP by 13% and glaucoma medications by 12%. For PXG, 5 studies (total, 132 patients; follow-up, 34 months) showed phacoemulsification reduced IOP by 20% and glaucoma medications by 35%. For chronic PACG, 12 studies (total, 495 patients; follow-up, 16 months) showed phacoemulsification reduced IOP by 30% and glaucoma medications by 58%. Patients with acute PACG (4 studies; total, 119 patients; follow-up, 24 months) had a 71% reduction from presenting IOP and rarely required long-term glaucoma medications when phacoemulsification was performed soon after medical reduction of IOP. Trabeculectomy after phacoemulsification was uncommon; the median rate reported within 6 to 24 months of follow-up in patients with controlled POAG, PXG, or PACG was 0% and was 7% in patients with uncontrolled chronic PACG.Phacoemulsification typically results in small, moderate, and marked reductions of IOP and medications for patients with POAG, PXG, and PACG, respectively, and using 1 to 2 medications before surgery. Trabeculectomy within 6 to 24 months after phacoemulsification is rare in such patients. However, reports on its effects in eyes with advanced disease or poor IOP control before surgery are few, particularly for POAG and PXG.

  View details for DOI 10.1016/j.ophtha.2015.03.021

  View details for Web of Science ID 000356621700012

  View details for PubMedID 25943711

• Self-reported Calcium Supplementation and Age-Related Macular Degeneration JAMA OPHTHALMOLOGY Kakigi, C. L., Singh, K., Wang, S. Y., Enanoria, W. T., Lin, S. C. 2015; 133 (7): 746-754

  Abstract

  Despite widespread use of calcium supplementation among elderly people, little is known about the association between such consumption and the prevalence of age-related macular degeneration (AMD) in the United States.To investigate the association between self-reported supplementary calcium consumption and the prevalence of AMD in a representative US sample.This cross-sectional study included 3191 participants 40 years and older in the 2007-2008 National Health and Nutrition Examination Survey (NHANES) who were evaluated for the presence or absence of AMD by fundus photography. Participants were interviewed regarding use of dietary supplements and antacids during the 30-day period preceding enrollment. Self-reported supplementary intake of calcium was aggregated and divided into quintiles. Fundus photographs were graded for the presence or absence of AMD. Information regarding demographics, comorbidities, and health-related behaviors was obtained via interview. Multivariable logistic regression models were created to determine the odds of an AMD diagnosis among participants in each quintile of self-reported calcium vs participants not self-reporting supplementary calcium consumption after adjusting for confounders.Self-reported use of calcium supplements.Presence or absence of AMD by fundus photography.A total of 248 participants (7.8%) were diagnosed with AMD. Mean ages were 67.2 years for those with AMD and 55.8 for those without AMD. After adjustment for potential confounding variables, study participants who self-reported consumption of more than 800 mg/d of supplementary calcium were found to have higher odds of an AMD diagnosis based on fundus photography evaluation compared with those not self-reporting supplementary calcium consumption (odds ratio, 1.85; 95% CI, 1.25-2.75). The association between self-reported supplementary calcium intake and AMD was stronger in older than younger individuals (odds ratio, 2.63; 95% CI, 1.52-4.54). A clear dose-response association between the quintiles of self-reported supplementary calcium intake and AMD was not established.Self-reported supplementary calcium consumption is associated with increased prevalence of AMD, with the findings suggesting a threshold rather than a dose-response relationship. The stronger association in older individuals may be due to relatively longer duration of calcium supplementation in older individuals.

  View details for DOI 10.1001/jamaophthalmol.2015.0514

  View details for Web of Science ID 000357823100021

  View details for PubMedID 25856252

• A randomised, controlled comparison of latanoprostene bunod and latanoprost 0.005% in the treatment of ocular hypertension and open angle glaucoma: the VOYAGER study BRITISH JOURNAL OF OPHTHALMOLOGY Weinreb, R. N., Ong, T., Sforzolini, B. S., Vittitow, J. L., Singh, K., Kaufman, P. L. 2015; 99 (6): 738-745

  Abstract

  To assess the efficacy and safety of latanoprostene bunod (LBN) compared with latanoprost 0.005%, and to determine the optimum drug concentration(s) of LBN in reducing intraocular pressure (IOP) in subjects with open angle glaucoma or ocular hypertension.Randomised, investigator-masked, parallel-group, dose-ranging study. Subjects instilled one drop of study medication in the study eye once daily each evening for 28 days and completed five study visits. The primary efficacy endpoint was the reduction in mean diurnal IOP at Day 28.Of the 413 subjects randomised (LBN 0.006%, n=82; LBN 0.012%, n=85; LBN 0.024%, n=83; LBN 0.040%, n=81; latanoprost, n=82), 396 subjects completed the study. Efficacy for LBN was dose-dependent reaching a plateau at 0.024%-0.040%. LBN 0.024% led to significantly greater reductions in diurnal IOP compared with latanoprost at the primary endpoint, Day 28 (p=0.005), as well as Days 7 (p=0.033) and 14 (p=0.015). The incidence of adverse events, mostly mild and transient, was numerically higher in the LBN treatment groups compared with the latanoprost group. Hyperaemia was similar across treatments.LBN 0.024% dosed once daily was the lower of the two most effective concentrations evaluated, with significantly greater IOP lowering and comparable side effects relative to latanoprost 0.005%. LBN dosed once daily for 28 days was well tolerated.NCT01223378.

  View details for DOI 10.1136/bjophthalmol-2014-305908

  View details for Web of Science ID 000354950600005

  View details for PubMedID 25488946

• Quantitative Measurement of Fixation Stability During RareBit Perimetry and Humphrey Visual Field Testing. Journal of glaucoma Lin, S. R., Lai, I. N., Dutta, S., Singh, K., Chang, R. T. 2015; 24 (2): 100-104

  Abstract

  To compare fixation stability and fixation loss between the Humphrey Field Analyzer (HVF, static fixation target) and the RareBit computer-based perimeter (RBP, kinetic fixation target) during visual field testing.Fourteen healthy volunteer subjects wore an ASL Mobile Gaze Tracker as they completed HVF 10-2 and RareBit central field tests in a random order. Fixation stability, defined as the average distance from the fixation target to the subject's gaze location, was calculated using data from the processed video capture. Fixation loss, defined as eye closure or a deviation of >20 degrees from the fixation target, was also measured. All subjects were surveyed regarding test preference.Use of the RBP kinetic target was associated with 18% improved fixation stability compared with the HVF static target (P=0.02). Nine of 14 study subjects demonstrated better fixation with RBP compared with HVF. Subjects demonstrated decreased fixation loss during RBP (0.9 s) compared with HVF (10.0 s) (P=0.002). Eighty-six percent of study subjects preferred RBP over HVF.Use of the RBP kinetic fixation target is associated with consistent fixation stability and decreased fixation loss compared with the HVF static target. This improvement in fixation stability may result from decreased perception interference (Ganzfeld, Troxler, and binocular rivalry effects), and may help account for the greater comfort reported with RBP compared with HVF.

  View details for DOI 10.1097/IJG.0b013e31829d9b41

  View details for PubMedID 25642647

• Clinical Impact of 8 Prospective, Randomized, Multicenter Glaucoma Trials JOURNAL OF GLAUCOMA Panarelli, J. F., Banitt, M. R., Sidoti, P. A., Budenz, D. L., Singh, K. 2015; 24 (1): 64-68

  Abstract

  PURPOSE:: To determine the impact of 8 multicenter randomized clinical trials (RCTs) on glaucoma practice. METHODS:: An electronic survey was distributed to the members of the American Glaucoma Society (AGS). Each participant was asked 2 study-specific questions and 1 standard question common to all 8 RCTs assessing the study's impact on clinical practice. RCTs included in the survey were the Advanced Glaucoma Intervention Study (AGIS), Collaborative Initial Glaucoma Treatment Study (CIGTS), Collaborative Normal Tension Glaucoma (CNTG) Study, European Glaucoma Prevention Study (EGPS), Early Manifest Glaucoma Trial (EMGT), Glaucoma Laser Trial (GLT), Ocular Hypertension Treatment Study (OHTS), and Tube Versus Trabeculectomy (TVT) Study. A 5-point Likert scale was used for rating all responses. The practice setting and duration of glaucoma practice was determined for all AGS members who responded. RESULTS:: A total of 206 (23.0%) of 894 AGS members participated in the survey. Among those who responded, 46.4% were self classified as academic practitioners and 53.6% worked in a private practice setting. Mean Likert scores for the standard question evaluating the overall impact of the RCT were OHTS 4.47, CNTG Study 4.13, AGIS 3.78, TVT Study 3.53, EMGT 3.48, CIGTS 3.44, GLT 3.39, and 2.69 EGPS. CONCLUSIONS:: Substantial differences were observed in the clinical impact of several RCTs in glaucoma. The reported impact of each study likely reflects several factors including study timing, design, conduct, and interpretation of results.

  View details for DOI 10.1097/IJG.0b013e318295200b

  View details for Web of Science ID 000346844000011

  View details for PubMedID 23632410

• DNA Copy Number Variants of Known Glaucoma Genes in Relation to Primary Open-Angle Glaucoma INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Liu, Y., Garrett, M. E., Yaspan, B. L., Bailey, J. C., Loomis, S. J., Brilliant, M., Budenz, D. L., Christen, W. G., Fingert, J. H., Gaasterland, D., Gaasterland, T., Kang, J. H., Lee, R. K., Lichter, P., Moroi, S. E., Realini, A., Richards, J. E., Schuman, J. S., Scott, W. K., Singh, K., Sit, A. J., Vollrath, D., Weinreb, R., Wollstein, G., Zack, D. J., Zhang, K., Pericak-Vance, M. A., Haines, J. L., Pasquale, L. R., Wiggs, J. L., Allingham, R. R., Ashley-Koch, A. E., Hauser, M. A. 2014; 55 (12): 8251-8258

  Abstract

  We examined the role of DNA copy number variants (CNVs) of known glaucoma genes in relation to primary open angle glaucoma (POAG).Our study included DNA samples from two studies (NEIGHBOR and GLAUGEN). All the samples were genotyped with the Illumina Human660W_Quad_v1 BeadChip. After removing non-blood-derived and amplified DNA samples, we applied quality control steps based on the mean Log R Ratio and the mean B allele frequency. Subsequently, data from 3057 DNA samples (1599 cases and 1458 controls) were analyzed with PennCNV software. We defined CNVs as those ≥5 kilobases (kb) in size and interrogated by ≥5 consecutive probes. We further limited our investigation to CNVs in known POAG-related genes, including CDKN2B-AS1, TMCO1, SIX1/SIX6, CAV1/CAV2, the LRP12-ZFPM2 region, GAS7, ATOH7, FNDC3B, CYP1B1, MYOC, OPTN, WDR36, SRBD1, TBK1, and GALC.Genomic duplications of CDKN2B-AS1 and TMCO1 were each found in a single case. Two cases carried duplications in the GAS7 region. Genomic deletions of SIX6 and ATOH7 were each identified in one case. One case carried a TBK1 deletion and another case carried a TBK1 duplication. No controls had duplications or deletions in these six genes. A single control had a duplication in the MYOC region. Deletions of GALC were observed in five cases and two controls.The CNV analysis of a large set of cases and controls revealed the presence of rare CNVs in known POAG susceptibility genes. Our data suggest that these rare CNVs may contribute to POAG pathogenesis and merit functional evaluation.

  View details for DOI 10.1167/iovs.14-15712

  View details for Web of Science ID 000347222300062

• Association Between Serum Ferritin and Glaucoma in the South Korean Population JAMA OPHTHALMOLOGY Lin, S., Wang, S. Y., Yoo, C., Singh, K., Lin, S. C. 2014; 132 (12): 1414-1420

  Abstract

  Evidence suggests that altered iron metabolism may be associated with oxidative damage to several organ systems, including the eye. Supplementary iron consumption is also associated with greater odds of self-reported glaucoma.To investigate the association between serum ferritin level and the likelihood of a glaucoma diagnosis in a cross-sectional, population-based study.Data were collected from 17,476 participants in the first and second years of the Fifth Korea National Health and Nutrition Examination Survey, a cross-sectional study of the South Korean population conducted from January 1, 2010, through December 31, 2011. Data pertaining to the serum ferritin level were aggregated and divided into quartiles. Demographic, comorbidity, and health-related behavior information was obtained via interview.The presence or absence of glaucoma. The definition of glaucoma was based on criteria established by the International Society of Geographical and Epidemiological Ophthalmology.Participants whose serum ferritin level was greater than 61 ng/mL (to convert to picomoles per liter, multiply by 2.247) had significantly higher odds of a glaucoma diagnosis when compared with those with a level less than 31 ng/mL, after adjustment for potential confounders (ferritin levels of 31-61 ng/mL: odds ratio [OR], 1.17; 95% CI, 0.84-1.62; ferritin levels of 62-112 ng/mL: OR, 1.60; 95% CI, 1.16-2.20; and ferritin levels of 113-3018 ng/mL: OR, 1.89; 95% CI, 1.32-2.72).Our study reveals that a higher serum ferritin level was associated with greater odds of glaucoma in a representative sample of the South Korean population, even at levels normally observed in the general population. This novel finding may help elucidate the pathogenesis and lead to novel therapeutic approaches for glaucomatous disease.

  View details for DOI 10.1001/jamaophthalmol.2014.2876

  View details for Web of Science ID 000346176400006

  View details for PubMedID 25171442

• Parallel rarebits: A novel, large-scale visual field screening method CLINICAL AND EXPERIMENTAL OPTOMETRY Lin, S. R., Fijalkowski, N., Lin, B. R., Li, F., Singh, K., Chang, R. T. 2014; 97 (6): 528-533

  View details for DOI 10.1111/cxo.12221

  View details for Web of Science ID 000344172900008

• Special Commentary: Food and Drug Administration and American Glaucoma Society Co-sponsored Workshop The Validity, Reliability, and Usability of Glaucoma Imaging Devices OPHTHALMOLOGY Meier, K. L., Greenfield, D. S., Hilmantel, G., Kahook, M. Y., Lin, C., Rorer, E. M., Singh, K., Tarver, M. E., Weinreb, R. N., Eydelman, M. B., Liebmann, J. M. 2014; 121 (11): 2116-2123

  View details for DOI 10.1016/j.ophtha.2014.05.024

  View details for Web of Science ID 000344480400015

  View details for PubMedID 25085628

• Pediatric Glaucoma Surgery A Report by the American Academy of Ophthalmology OPHTHALMOLOGY Chen, T. C., Chen, P. P., Francis, B. A., Junk, A. K., Smith, S. D., Singh, K., Lin, S. C. 2014; 121 (11): 2107-2115

  Abstract

  To review the current published literature to evaluate the success rates and long-term problems associated with surgery for pediatric glaucoma.Literature searches of the PubMed and Cochrane Library databases were last conducted in May 2012. The search yielded 838 potentially relevant citations, of which 273 were in non-English languages. The titles and abstracts of these articles were reviewed by the authors, and 364 were selected for possible further review. Members of the Ophthalmic Technology Assessment Committee Glaucoma Panel reviewed the full text of these articles and used the 36 that met inclusion and exclusion criteria for this Ophthalmic Technology Assessment. There were no studies on the topic that provided level I evidence. The assessment included only level II and level III studies.Surgeons treat pediatric glaucoma most commonly with goniotomy, trabeculotomy, trabeculectomy, combined trabeculotomy and trabeculectomy, tube shunt surgery, cyclodestruction, and deep sclerectomy. Certain surgical options seem better for specific diagnoses, such as primary congenital glaucoma, aphakic glaucoma, and glaucomas associated with other ocular or systemic anomalies.There are many surgical options for the treatment of the pediatric glaucomas. The relative efficacy of these various procedures for particular diagnoses and clinical situations should be weighed against the specific risks associated with the procedures for individual patients.

  View details for DOI 10.1016/j.ophtha.2014.05.010

  View details for Web of Science ID 000344480400014

  View details for PubMedID 25066765

• Hypothesis-independent pathway analysis implicates GABA and Acetyl-CoA metabolism in primary open-angle glaucoma and normal-pressure glaucoma HUMAN GENETICS Bailey, J. N., Yaspan, B. L., Pasquale, L. R., Hauser, M. A., Kang, J. H., Loomis, S. J., Brilliant, M., Budenz, D. L., Christen, W. G., Fingert, J., Gaasterland, D., Gaasterland, T., Kraft, P., Lee, R. K., Lichter, P. R., Liu, Y., McCarty, C. A., Moroi, S. E., Richards, J. E., Realini, T., Schuman, J. S., Scott, W. K., Singh, K., Sit, A. J., Vollrath, D., Wollstein, G., Zack, D. J., Zhang, K., Pericak-Vance, M. A., Allingham, R. R., Weinreb, R. N., Haines, J. L., Wiggs, J. L. 2014; 133 (10): 1319-1330

  View details for DOI 10.1007/s00439-014-1468-7

  View details for Web of Science ID 000341828900009

• RELATIONSHIP BETWEEN GLAUCOMA AND ADMIXTURE IN POSTMENOPAUSAL AFRICAN AMERICAN WOMEN ETHNICITY & DISEASE Garcia, L., Qi, L., Singh, K., Kosoy, R., Nassir, R., Fijalkowski, N., Haan, M., Robbins, J., Seldin, M. F. 2014; 24 (4): 399-405

  Abstract

  To investigate the association between African admixture and glaucoma prevalence among African American women.Participants included 11616 African American women from the Women's Health Initiative Study (WHI) for whom admixture information was available and included 2548 who self-reported a diagnosis of glaucoma.Glaucoma.Significant association was observed between self-identified glaucoma status and admixture. However, this association was not significant in a model that included neighborhood socioeconomic status (NSES), hypertension, diabetes and body mass index (BMI). Self-identified glaucoma status was associated with diabetes that persisted after adjustment for admixture, NSES, hypertension, and BMI. Lower NSES was also associated with higher glaucoma risk but this association was marginal in the fully adjusted model and neither hypertension nor BMI showed association. When glaucoma status was limited to those reporting use or no use of appropriate ophthalmologic medication, no associations were observed in any of the models.This study failed to find an independent association of glaucoma status and African admixture and these findings suggest that the higher frequency glaucoma in African Americans may be largely due to other factors.

  View details for Web of Science ID 000363717400003

  View details for PubMedID 25417420

• Racial Disparities in Uncorrected and Undercorrected Refractive Error in the United States INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Qiu, M., Wang, S. Y., Singh, K., Lin, S. C. 2014; 55 (10)

  Abstract

  To identify risk factors for inadequately corrected refractive error in the United States.This cross-sectional study included 12,758 participants 12 years of age and older from the 2005 to 2008 National Health and Nutrition Examination Survey. The primary outcome was the proportion of individuals with inadequate refractive correction for whom refractive correction would result in a visual acuity of 20/40 or better. The primary predictor was race/ethnicity. Secondary predictors included age, sex, annual household income, education, insurance, type of refractive error, current corrective lens use, presenting and best corrected visual acuity, cataract surgery, glaucoma, and age-related macular degeneration.Overall, 50.6% of subjects had a refractive error which was correctable to 20/40 or better with refraction. The percentage of subjects with correctable refractive error who were inadequately corrected was 11.7%. Odds of inadequate refractive correction were significantly greater in Mexican Americans and non-Hispanic blacks than in their non-Hispanic white counterparts in all age groups, with the greatest disparity in the 12- to 19-year-old group. Other risk factors associated with inadequate refractive correction in adults but not in teenagers included low annual household income, low education, and lack of health insurance.Racial disparities in refractive error correction were most pronounced in those under 20 years of age, as well as in adults with low annual household income, low education level, and lack of health insurance. Targeted efforts to provide culturally appropriate education, accessible vision screening, appropriate refractive correction, and routine follow-up to these medically underserved groups should be pursued as a public health strategy.

  View details for DOI 10.1167/iovs.13-12662

  View details for Web of Science ID 000344730500049

  View details for PubMedID 25249602

• Hypothesis-independent pathway analysis implicates GABA and acetyl-CoA metabolism in primary open-angle glaucoma and normal-pressure glaucoma. Human genetics Bailey, J. N., Yaspan, B. L., Pasquale, L. R., Hauser, M. A., Kang, J. H., Loomis, S. J., Brilliant, M., Budenz, D. L., Christen, W. G., Fingert, J., Gaasterland, D., Gaasterland, T., Kraft, P., Lee, R. K., Lichter, P. R., Liu, Y., McCarty, C. A., Moroi, S. E., Richards, J. E., Realini, T., Schuman, J. S., Scott, W. K., Singh, K., Sit, A. J., Vollrath, D., Wollstein, G., Zack, D. J., Zhang, K., Pericak-Vance, M. A., Allingham, R. R., Weinreb, R. N., Haines, J. L., Wiggs, J. L. 2014; 133 (10): 1319-1330

  Abstract

  Primary open-angle glaucoma (POAG) is a leading cause of blindness worldwide. Using genome-wide association single-nucleotide polymorphism data from the Glaucoma Genes and Environment study and National Eye Institute Glaucoma Human Genetics Collaboration comprising 3,108 cases and 3,430 controls, we assessed biologic pathways as annotated in the KEGG database for association with risk of POAG. After correction for genic overlap among pathways, we found 4 pathways, butanoate metabolism (hsa00650), hematopoietic cell lineage (hsa04640), lysine degradation (hsa00310) and basal transcription factors (hsa03022) related to POAG with permuted p < 0.001. In addition, the human leukocyte antigen (HLA) gene family was significantly associated with POAG (p < 0.001). In the POAG subset with normal-pressure glaucoma (NPG), the butanoate metabolism pathway was also significantly associated (p < 0.001) as well as the MAPK and Hedgehog signaling pathways (hsa04010 and hsa04340), glycosaminoglycan biosynthesis-heparan sulfate pathway (hsa00534) and the phenylalanine, tyrosine and tryptophan biosynthesis pathway (hsa0400). The butanoate metabolism pathway overall, and specifically the aspects of the pathway that contribute to GABA and acetyl-CoA metabolism, was the only pathway significantly associated with both POAG and NPG. Collectively these results implicate GABA and acetyl-CoA metabolism in glaucoma pathogenesis, and suggest new potential therapeutic targets.

  View details for DOI 10.1007/s00439-014-1468-7

  View details for PubMedID 25037249

• Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma EYE Kang, J. H., Loomis, S. J., Yaspan, B. L., BAILEY, J. C., Weinreb, R. N., Lee, R. K., Lichter, P. R., Budenz, D. L., Liu, Y., Realini, T., Gaasterland, D., Gaasterland, T., Friedman, D. S., McCarty, C. A., Moroi, S. E., Olson, L., Schuman, J. S., Singh, K., Vollrath, D., Wollstein, G., Zack, D. J., Brilliant, M., Sit, A. J., Christen, W. G., Fingert, J., Forman, J. P., Buys, E. S., Kraft, P., Zhang, K., Allingham, R. R., Pericak-Vance, M. A., Richards, J. E., Hauser, M. A., Haines, J. L., Wiggs, J. L., Pasquale, L. R. 2014; 28 (6): 662-671

  Abstract

  AimsVascular perfusion may be impaired in primary open-angle glaucoma (POAG); thus, we evaluated a panel of markers in vascular tone-regulating genes in relation to POAG.MethodsWe used Illumina 660W-Quad array genotype data and pooled P-values from 3108 POAG cases and 3430 controls from the combined National Eye Institute Glaucoma Human Genetics Collaboration consortium and Glaucoma Genes and Environment studies. Using information from previous literature and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, we compiled single-nucleotide polymorphisms (SNPs) in 186 vascular tone-regulating genes. We used the 'Pathway Analysis by Randomization Incorporating Structure' analysis software, which performed 1000 permutations to compare the overall pathway and selected genes with comparable randomly generated pathways and genes in their association with POAG.ResultsThe vascular tone pathway was not associated with POAG overall or POAG subtypes, defined by the type of visual field loss (early paracentral loss (n=224 cases) or only peripheral loss (n=993 cases)) (permuted P≥0.20). In gene-based analyses, eight were associated with POAG overall at permuted P<0.001: PRKAA1, CAV1, ITPR3, EDNRB, GNB2, DNM2, HFE, and MYL9. Notably, six of these eight (the first six listed) code for factors involved in the endothelial nitric oxide synthase activity, and three of these six (CAV1, ITPR3, and EDNRB) were also associated with early paracentral loss at P<0.001, whereas none of the six genes reached P<0.001 for peripheral loss only.DiscussionAlthough the assembled vascular tone SNP set was not associated with POAG, genes that code for local factors involved in setting vascular tone were associated with POAG.

  View details for DOI 10.1038/eye.2014.42

  View details for Web of Science ID 000338340200004

• Open-angle Glaucoma in Filipino and White Americans: A Comparative Study JOURNAL OF GLAUCOMA Sales, C. S., Lee, R. Y., Agadzi, A. K., Hee, M. R., Singh, K., Lin, S. C. 2014; 23 (4): 246-253

  Abstract

  PURPOSE:: To compare the frequency of open-angle glaucoma (OAG) subtypes between Filipino and white Americans in a general ophthalmology clinic population. PATIENTS AND METHODS:: In this retrospective cross-sectional epidemiologic study with prospective sampling, medical charts of 1113 patients aged 40 years or older (513 Filipinos, 600 whites) seen in 2008 were randomly sampled from 2 private comprehensive ophthalmology clinics. Glaucoma was diagnosed based on optic nerve appearance, visual field defects, and other ocular findings using the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) scheme. The normal-tension subtype of OAG [normal-tension glaucoma (NTG)] was defined by intraocular pressure ≤21 mm Hg as determined by review of medical records. RESULTS:: NTG comprised a greater proportion of all glaucomatous disease in Filipino subjects [Filipino (F) vs. white (W): 46.7% vs. 26.8%; P=0.02]. Filipinos were more commonly diagnosed with OAG and NTG than whites (F vs. W: OAG, 11.9% vs. 8.2%; NTG, 6.8% vs. 2.5%; P=0.04, 0.001, respectively). There was no significant difference in central corneal thickness between Filipino and white subjects with NTG (P=0.66). CONCLUSIONS:: Both OAG and NTG may be more common in Filipino Americans than in white Americans with the propensity for NTG being particularly high in the former relative to the latter group.

  View details for DOI 10.1097/IJG.0b013e318279b3e2

  View details for Web of Science ID 000334245600010

  View details for PubMedID 23221903

• Age-related macular degeneration and protective effect of HMG Co-A reductase inhibitors (statins): results from the National Health and Nutrition Examination Survey 2005-2008 EYE Barbosa, D. T., Mendes, T. S., Cintron-Colon, H. R., Wang, S. Y., Bhisitkul, R. B., Singh, K., Lin, S. C. 2014; 28 (4): 472-480

  Abstract

  To determine the association of hydroxymethylglutarylcoenzyme A (HMG Co-A) reductase inhibitor (statin) use with the prevalence of age-related macular degeneration (AMD).This cross-sectional study included 5604 participants in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2008, ≥ 40 years of age, who were ascertained with regard to the diagnosis of AMD, the use of statins, and comorbidities and health-related behaviors such as smoking.The mean age of participants denying or confirming a history of AMD was 68 (SEM 0.90) and 55 (SEM 0.36) years, respectively. Individuals 68 years of age or older who were classified as long-term users of statins had statistically significant less self-reported AMD (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.49-0.84; P=0.002), after adjusting for potential confounding variables. No significant association was found between the prevalence of AMD and statin consumption among subjects between 40 and 67 years of age (OR 1.61, 95% CI 0.85-3.03; P=0.137).Our results suggest a possible beneficial effect of statin intake for the prevention of AMD in individuals 68 years of age or older.

  View details for DOI 10.1038/eye.2014.8

  View details for Web of Science ID 000334360000016

  View details for PubMedID 24503725

• Glaucoma Screening Using Relative Afferent Pupillary Defect JOURNAL OF GLAUCOMA Charalel, R. A., Lin, H. S., Singh, K. 2014; 23 (3): 169-173

  Abstract

  PURPOSE:: To assess the relative afferent pupillary defect (RAPD) by swinging flashlight as a potentially useful screening test for glaucomatous optic neuropathy. METHODS:: One hundred seven subjects prospectively recruited from a mixed population of glaucomatous and nonglaucomatous patients were examined for a RAPD by 1 individual masked with regard to disease presence. All subjects underwent a swinging flashlight test with, when necessary, the aid of neutral density filters, to determine whether or not a RAPD was present. A determination of glaucoma diagnosis, as well as classification of disease stage, was subsequently assessed based upon review of history and ophthalmic examination. This clinical information regarding glaucomatous disease was ascertained without knowledge of study RAPD status. The acquisition of such clinical information and performance of swinging flashlight testing for RAPD was conducted by different individuals with the latter being a nonophthalmologist. RESULTS:: Statistical analysis demonstrated an odds ratio of 9.71 (95% CI, 3.72-25.40) for glaucomatous disease if a RAPD was present, with a sensitivity of 66.7% and a specificity of 82.9%. Subanalysis of patients who had not previously undergone cataract surgery revealed an odds ratio of 17.05 (95% CI, 4.73-61.44) for glaucomatous disease if a RAPD was present, with a sensitivity of 68.8% and a specificity of 88.6%. CONCLUSIONS:: RAPD screening by a swinging flashlight test with neutral density filters was moderately sensitive and strongly specific for glaucoma. Sensitivity, specificity, and predictive value improved when patients who had previously undergone cataract surgery were removed from the analysis.

  View details for DOI 10.1097/IJG.0b013e31826a9742

  View details for Web of Science ID 000332601000008

  View details for PubMedID 23296370

• Association between Visual Field Defects and Quality of Life in the United States. Ophthalmology Qiu, M., Wang, S. Y., Singh, K., Lin, S. C. 2014; 121 (3): 733-740

  Abstract

  To investigate the association between visual field defects and quality of life in the United States population.Cross-sectional study.A total of 5186 participants in the 2005 through 2008 National Health and Nutrition Examination Survey 40 years of age and older without a self-reported history of age-related macular degeneration or prior refractive surgery who had undergone frequency doubling technology perimetric testing.Frequency doubling technology perimetry was performed in both eyes. Results from the better eye were used to categorize subjects as normal or having mild, moderate, or severe visual field loss. Subjects completed surveys about their visual and physical functioning ability.Disability pertaining to 6 vision-related activities, 2 visual function questions, and 5 physical functioning domains.Eighty-one percent of subjects had normal visual fields and 10%, 7%, and 2% demonstrated mild, moderate, and severe visual field defects, respectively. Subjects with greater severity of visual field defects had greater difficulty with vision-related activities. Subjects with severe visual field defects demonstrated the greatest odds of difficulty with all 6 activities. The 2 activities impacted most adversely were daytime driving in familiar places (odds ratio [OR], 12.4; 95% confidence interval [CI], 6.1-25.1) and noticing objects off to the side when walking (OR, 7.7; 95% CI, 4.7-12.7). Subjects with severe visual field defects had greater odds of worrying about eyesight (OR, 3.4; 95% CI, 2.0-5.8) and being limited by vision in the time spent on daily activities (OR, 5.1; 95% CI, 3.0-8.5). Subjects with severe visual field defects demonstrated the greatest odds of difficulty with 3 physical function domains, including activities of daily living (OR, 2.45; 95% CI, 1.37-4.38), instrumental activities of daily living (OR, 2.45; 95% CI, 1.37-4.38), as well as leisure and social activities (OR, 3.29; 95% CI, 1.87-5.77).Greater severity of visual field abnormality was associated with significantly greater odds of disability with vision-related function and physical function. These findings support the necessity of routine screening to find those who may benefit from therapy to prevent progressive glaucomatous vision loss.

  View details for DOI 10.1016/j.ophtha.2013.09.043

  View details for PubMedID 24342021

• Association of CAV1/CAV2 Genomic Variants with Primary Open-Angle Glaucoma Overall and by Gender and Pattern of Visual Field Loss OPHTHALMOLOGY Loomis, S. J., Kang, J. H., Weinreb, R. N., Yaspan, B. L., Bailey, J. N., Gaasterland, D., Gaasterland, T., Lee, R. K., Lichter, P. R., Budenz, D. L., Liu, Y., Realini, T., Friedman, D. S., McCarty, C. A., Moroi, S. E., Olson, L., Schuman, J. S., Singh, K., Vollrath, D., Wollstein, G., Zack, D. J., Brilliant, M., Sit, A. J., Christen, W. G., Fingert, J., Kraft, P., Zhang, K., Allingham, R. R., Pericak-Vance, M. A., Richards, J. E., Hauser, M. A., Haines, J. L., Pasquale, L. R., Wiggs, J. L. 2014; 121 (2): 508-516

  Abstract

  The CAV1/CAV2 (caveolin 1 and caveolin 2) genomic region previously was associated with primary open-angle glaucoma (POAG), although replication among independent studies has been variable. The aim of this study was to assess the association between CAV1/CAV2 single nucleotide polymorphisms (SNPs) and POAG in a large case-control dataset and to explore associations by gender and pattern of visual field (VF) loss further.Case-control study.We analyzed 2 large POAG data sets: the Glaucoma Genes and Environment (GLAUGEN) study (976 cases, 1140 controls) and the National Eye Institute Glaucoma Human Genetics Collaboration (NEIGHBOR) consortium (2132 cases, 2290 controls).We studied the association between 70 SNPs located within the CAV1/CAV2 genomic region in the GLAUGEN and NEIGHBOR studies, both genotyped on the Illumina Human 660WQuadv1C BeadChip array and imputed with the Markov Chain Haplotyping algorithm using the HapMap 3 reference panel. We used logistic regression models of POAG in the overall population and separated by gender, as well as by POAG subtypes defined by type of VF defect (peripheral or paracentral). Results from GLAUGEN and NEIGHBOR were meta-analyzed, and a Bonferroni-corrected significance level of 7.7 × 10(-4) was used to account for multiple comparisons.Overall POAG, overall POAG by gender, and POAG subtypes defined by pattern of early VF loss.We found significant associations between 10 CAV1/CAV2 SNPs and POAG (top SNP, rs4236601; pooled P = 2.61 × 10(-7)). Of these, 9 were significant only in women (top SNP, rs4236601; pooled P = 1.59 × 10(-5)). Five of the 10 CAV1/CAV2 SNPs were associated with POAG with early paracentral VF (top SNP, rs17588172; pooled P = 1.07 × 10(-4)), and none of the 10 were associated with POAG with peripheral VF loss only or POAG among men.CAV1/CAV2 SNPs were associated significantly with POAG overall, particularly among women. Furthermore, we found an association between CAV1/CAV2 SNPs and POAG with paracentral VF defects. These data support a role for caveolin 1, caveolin 2, or both in POAG and suggest that the caveolins particularly may affect POAG pathogenesis in women and in patients with early paracentral VF defects.

  View details for DOI 10.1016/j.ophtha.2013.09.012

  View details for Web of Science ID 000330579200016

  View details for PubMedID 24572674

• Things Go Better with Cataract Surgery OPHTHALMOLOGY Singh, K. 2014; 121 (1): 1-1

  View details for DOI 10.1016/j.ophtha.2013.08.001

  View details for Web of Science ID 000329169500008

  View details for PubMedID 24388392

• Genomewide association study and meta-analysis of intraocular pressure Human Genetics Ozel, A., Moroi, S., Reed, D., Nika, M., Schmidt, C., Akbari, S., et al 2014; 1 (133): 41-57
• The impact of cataract surgery on glaucoma care CURRENT OPINION IN OPHTHALMOLOGY Shrivastava, A., Singh, K. 2014; 25 (1): 19-25

  Abstract

  To summarize the effects of cataract surgery on the management of glaucoma, in terms of the effect on both the intraocular pressure (IOP) and postoperative diagnostic as well as therapeutic considerations.Recent evidence corroborates prior data demonstrating significant and sustained IOP reduction after cataract extraction, particularly in closed-angle variants of glaucoma, but also in individuals with open-angle glaucoma or ocular hypertension. Performing cataract surgery after trabeculectomy increases the odds of filtration failure with the likelihood of this adverse effect being inversely proportional to the duration between the glaucoma and cataract procedures. Although cataract has a significant effect on the results of visual field testing, the Visual Field Index may be less influenced than other parameters such as the mean and pattern deviation. The accuracy of time-domain ocular coherence tomography and spectral-domain ocular coherence tomography are also negatively impacted by cataract.Considering cataract surgery as an IOP-lowering procedure may be appropriate in select patients. Performing cataract extraction prior to glaucoma surgery has numerous benefits. The sequence of the procedures performed has implications in terms of complications, surgical success, and diagnostics. Reestablishing perimetric and structural baselines with imaging modalities is appropriate after cataract surgery is performed in glaucoma patients.

  View details for DOI 10.1097/ICU.0000000000000010

  View details for Web of Science ID 000327996600004

  View details for PubMedID 24270598

• Corneal changes after a single session of selective laser trabeculoplasty for open-angle glaucoma EYE Lee, J. W., Chan, J. C., Chang, R. T., Singh, K., Liu, C. C., Gangwani, R., Wong, M. O., Lai, J. S. 2014; 28 (1): 47-52

  Abstract

  To investigate the changes in endothelial cell count, central corneal thickness (CCT), and refractive error after a session of selective laser trabeculoplasty (SLT) for open angle glaucoma (OAG).This prospective cohort study recruited 111 eyes of 66 consecutive subjects with OAG. Subjects received SLT to 360° of the trabecular meshwork. Endothelial cell count, CCT, and spherical equivalent were measured at baseline before SLT as well as at 1 week and 1 month post SLT. A repeated measure nested ANOVA with Tukey's multiple comparison test was performed to compare the outcome measures before and after SLT.In 111 eyes of 66 subjects, the mean number of laser applications per treatment was 166.9 ± 41.4 with a mean energy level of 1.0 ± 0.07 mJ. The mean endothelial cell count decreased significantly from 2465.0 ± 334.0 cells/mm(2) at baseline to 2355.0 ± 387.0 cells/mm(2) at 1 week (P=0.0004) but increased to baseline levels at 1 month post SLT (2424.0 ± 379.4 cells/mm(2), P=0.3). The CCT, which decreased from a baseline of 549.4 ± 37.6 to 543.9 ± 40.2 μm at 1 week post SLT (P=0.02), also returned to the baseline level by 1 month (P=0.2). The spherical equivalent was static from baseline. A positive correlation was found between total laser energy and CCT at 1 month post treatment (r=0.3, P=0.005).The transient reductions in endothelial cell count and CCT following SLT returned to baseline levels 1 month after the procedure. Patients undergoing SLT should be aware of the risk of potential corneal changes.

  View details for DOI 10.1038/eye.2013.231

  View details for Web of Science ID 000329440100008

  View details for PubMedID 24136571

• Evaluation of the Anterior Chamber Angle in Glaucoma A Report by the American Academy of Ophthalmology OPHTHALMOLOGY Smith, S. D., Singh, K., Lin, S. C., Chen, P. P., Chen, T. C., Francis, B. A., Jampel, H. D. 2013; 120 (10): 1985-1997

  Abstract

  To assess the published literature pertaining to the association between anterior segment imaging and gonioscopy and to determine whether such imaging aids in the diagnosis of primary angle closure (PAC).Literature searches of the PubMed and Cochrane Library databases were last conducted on July 6, 2011. The searches yielded 371 unique citations. Members of the Ophthalmic Technology Assessment Committee Glaucoma Panel reviewed the titles and abstracts of these articles and selected 134 of possible clinical significance for further review. The panel reviewed the full text of these articles and identified 79 studies meeting the inclusion criteria, for which the panel methodologist assigned a level of evidence based on a standardized grading scheme adopted by the American Academy of Ophthalmology. Three, 70, and 6 studies were rated as providing level I, II, and III evidence, respectively.Quantitative and qualitative parameters defined from ultrasound biomicroscopy (UBM), anterior segment optical coherence tomography (OCT), Scheimpflug photography, and the scanning peripheral anterior chamber depth analyzer (SPAC) demonstrate a strong association with the results of gonioscopy. There is substantial variability in the type of information obtained from each imaging method. Imaging of structures posterior to the iris is possible only with UBM. Direct imaging of the anterior chamber angle (ACA) is possible using UBM and OCT. The ability to acquire OCT images in a completely dark environment allows greater sensitivity in detecting eyes with appositional angle closure. Noncontact imaging using OCT, Scheimpflug photography, or SPAC makes these methods more attractive for large-scale PAC screening than contact imaging using UBM.Although there is evidence suggesting that anterior segment imaging provides useful information in the evaluation of PAC, none of these imaging methods provides sufficient information about the ACA anatomy to be considered a substitute for gonioscopy. Longitudinal studies are needed to validate the diagnostic significance of the parameters measured by these instruments for prospectively identifying individuals at risk for PAC.Proprietary or commercial disclosure may be found after the references.

  View details for DOI 10.1016/j.ophtha.2013.05.034

  View details for Web of Science ID 000325086400014

  View details for PubMedID 23978623

• Patient-Related and System-Related Barriers to Glaucoma Follow-up in a County Hospital Population INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Lee, B. W., Murakami, Y., Duncan, M. T., Kao, A. A., Huang, J., Lin, S., Singh, K. 2013; 54 (10): 6542-6548

  Abstract

  To identify the barriers to glaucoma follow-up and to assess how ethnicity influences the effect of such barriers among patients in a county hospital population.This cross-sectional study included 152 patients, 76 with poor clinic follow-up and 76 with good clinic follow-up, who were recruited at the San Francisco General Hospital glaucoma clinic as part of a case-control study. All subjects were required to be established patients with glaucoma initially seen and diagnosed in the clinic at least 1 year before enrollment. An oral questionnaire pertaining to the barriers to follow-up for glaucoma, as well as patient ethnicity, was administered to all participating subjects. The main outcome measure was the prevalence of significant barriers to follow-up, both overall and stratified by ethnicity.The most prevalent barriers to follow-up included long clinic waiting times (75%), appointment scheduling difficulties (38%), the effect of other medical or physical comorbidities (29%), and difficulties related to medical interpretation (23%). While several barriers were cited as being important across different ethnicities, Latinos and Asian-Pacific Islanders were particularly affected by difficulties related to medical interpretation (P = 0.0001) and long waiting times in the clinic (P = 0.048).Understanding patient-reported barriers to glaucoma follow-up and their variation based on ethnicity may give providers insight as to why patients do not adhere to follow-up recommendations. Strategies to improve follow-up may include reduced clinic wait times, simplified appointment scheduling, and provision of appropriate education and counseling regardless of the patient's native language and ethnicity.

  View details for DOI 10.1167/iovs.13-12108

  View details for Web of Science ID 000326567700011

  View details for PubMedID 23982843

• Glaucoma Prevalence and the Intake of Iron and Calcium in a Population-based Study CURRENT EYE RESEARCH Wang, S. Y., Singh, K., Lin, S. C. 2013; 38 (10): 1049-1056

  Abstract

  Previous work has suggested a possible relationship between nutritional supplementation with iron and calcium, and a diagnosis of glaucoma. The present study investigates the association between dietary and total calcium and iron consumption with a diagnosis of glaucoma.This cross-sectional study included 6316 participants in the National Health and Nutrition Examination Survey (NHANES 2005-2008), age 40 or older, who participated in the dietary interview portion of NHANES. Intake of the oxidants calcium and iron was assessed using the National Cancer Institute Method of analyzing data from multiple 24-h dietary recall interviews. Participants self-reported the presence or absence of glaucoma as well as information pertaining to demographics, health-related behaviors and comorbidities.Adjusted odds of glaucoma increased with higher total consumption of calcium (p-trend <0.0001) and iron (p-trend <0.0001). Adjusted odds of glaucoma was significantly greater for total calcium intake at the third (OR 1.58, 95% CI 1.32-1.89) and fourth quintile levels (OR 1.21, 95% CI 1.03-1.43) and for total iron intake at the fourth (OR 2.95, 95% CI 2.52-3.45) and fifth quintile levels (OR 1.58, 95% CI 1.36-1.83), compared with the corresponding lowest quintile of intake. In contrast, a tendency towards decreased odds of glaucoma was observed with increasing dietary calcium (p-trend = 0.0008) and iron intake (p-trend = 0.0022).While greater total consumption of calcium and iron may be associated with increased odds of glaucoma, dietary rather than supplemental consumption of these oxidants was found to be associated with lower odds of glaucoma. Additional research is necessary to elucidate the relationship between glaucoma and oxidant intake from foods versus supplements, and to prospectively evaluate whether oxidant intake is related to glaucoma incidence and progression.

  View details for DOI 10.3109/02713683.2013.803124

  View details for Web of Science ID 000323719500006

  View details for PubMedID 23790096

• The NEIGHBOR Consortium Primary Open-Angle Glaucoma Genome-wide Association Study: Rationale, Study Design, and Clinical Variables JOURNAL OF GLAUCOMA Wiggs, J. L., Hauser, M. A., Abdrabou, W., Allingham, R. R., Budenz, D. L., DelBono, E., Friedman, D. S., Kang, J. H., Gaasterland, D., Gaasterland, T., Lee, R. K., Lichter, P. R., Loomis, S., Liu, Y., McCarty, C., Medeiros, F. A., Moroi, S. E., Olson, L. M., Realini, A., Richards, J. E., Rozsa, F. W., Schuman, J. S., Singh, K., Stein, J. D., Vollrath, D., Weinreb, R. N., Wollstein, G., Yaspan, B. L., Yoneyama, S., Zack, D., Zhang, K., Pericak-Vance, M., Pasquale, L. R., Haines, J. L. 2013; 22 (7): 517-525

  Abstract

  Primary open-angle glaucoma (POAG) is a common disease with complex inheritance. The identification of genes predisposing to POAG is an important step toward the development of novel gene-based methods of diagnosis and treatment. Genome-wide association studies (GWAS) have successfully identified genes contributing to complex traits such as POAG however, such studies frequently require very large sample sizes, and thus, collaborations and consortia have been of critical importance for the GWAS approach. In this report we describe the formation of the NEIGHBOR consortium, the harmonized case control definitions used for a POAG GWAS, the clinical features of the cases and controls, and the rationale for the GWAS study design.

  View details for DOI 10.1097/IJG.0b013e31824d4fd8

  View details for Web of Science ID 000324388300003

  View details for PubMedID 22828004

• The Association Between Compliance With Recommended Follow-up and Glaucomatous Disease Severity in a County Hospital Population AMERICAN JOURNAL OF OPHTHALMOLOGY Ung, C., Murakami, Y., Zhang, E., Alfaro, T., Zhang, M., Seider, M. I., Singh, K., Lin, S. C. 2013; 156 (2): 362-369

  Abstract

  PURPOSE: To assess the association between insufficient follow-up and clinical parameters such as disease severity and medication use among glaucoma patients at a metropolitan county hospital. DESIGN: Cross-sectional study. METHODS: Two-hundred and six patients with established glaucoma were recruited from San Francisco General Hospital. Subjects were classified based on compliance with recommended follow-up examination intervals over the year preceding commencement of the study, as determined by patient medical records. Glaucoma severity was determined based on the American Academy of Ophthalmology Preferred Practice Patterns guidelines. Multivariate logistic regression analysis was used to assess the relationship between adherence with follow-up visits and disease severity. RESULTS: After adjustment for the impact of potential confounding variables, subjects with severe glaucomatous disease were found to have been less adherent to their recommended follow-up than those patients with mild or moderate glaucomatous disease (adjusted OR 1.89, 95% CI 1.21-2.94; P = .01). Subjects who were on glaucoma medications were found to be less adherent to follow-up recommendations (adjusted OR 3.29, 95% CI 1.41-7.65, P = .01). CONCLUSION: Subjects with poor follow-up adherence were significantly more likely to have severe glaucomatous disease, suggesting that poor follow-up may contribute to disease worsening or, alternatively, those with more severe disease are less inclined to follow up at appropriate intervals.

  View details for DOI 10.1016/j.ajo.2013.03.005

  View details for Web of Science ID 000322748200022

  View details for PubMedID 23601654

• Estrogen pathway polymorphisms in relation to primary open angle glaucoma: An analysis accounting for gender from the United States MOLECULAR VISION Pasquale, L. R., Loomis, S. J., Weinreb, R. N., Kang, J. H., Yaspan, B. L., Bailey, J. C., Gaasterland, D., Gaasterland, T., Lee, R. K., Scott, W. K., Lichter, P. R., Budenz, D. L., Liu, Y., Realini, T., Friedman, D. S., McCarty, C. A., Moroi, S. E., Olson, L., Schuman, J. S., Singh, K., Vollrath, D., Wollstein, G., Zack, D. J., Brilliant, M., Sit, A. J., Christen, W. G., Fingert, J., Kraft, P., Zhang, K., Allingham, R. R., Pericak-Vance, M. A., Richards, J. E., Hauser, M. A., Haines, J. L., Wiggs, J. L. 2013; 19: 1471-1481

  Abstract

  Circulating estrogen levels are relevant in glaucoma phenotypic traits. We assessed the association between an estrogen metabolism single nucleotide polymorphism (SNP) panel in relation to primary open angle glaucoma (POAG), accounting for gender.We included 3,108 POAG cases and 3,430 controls of both genders from the Glaucoma Genes and Environment (GLAUGEN) study and the National Eye Institute Glaucoma Human Genetics Collaboration (NEIGHBOR) consortium genotyped on the Illumina 660W-Quad platform. We assessed the relation between the SNP panels representative of estrogen metabolism and POAG using pathway- and gene-based approaches with the Pathway Analysis by Randomization Incorporating Structure (PARIS) software. PARIS executes a permutation algorithm to assess statistical significance relative to the pathways and genes of comparable genetic architecture. These analyses were performed using the meta-analyzed results from the GLAUGEN and NEIGHBOR data sets. We evaluated POAG overall as well as two subtypes of POAG defined as intraocular pressure (IOP) ≥22 mmHg (high-pressure glaucoma [HPG]) or IOP <22 mmHg (normal pressure glaucoma [NPG]) at diagnosis. We conducted these analyses for each gender separately and then jointly in men and women.Among women, the estrogen SNP pathway was associated with POAG overall (permuted p=0.006) and HPG (permuted p<0.001) but not NPG (permuted p=0.09). Interestingly, there was no relation between the estrogen SNP pathway and POAG when men were considered alone (permuted p>0.99). Among women, gene-based analyses revealed that the catechol-O-methyltransferase gene showed strong associations with HTG (permuted gene p≤0.001) and NPG (permuted gene p=0.01).The estrogen SNP pathway was associated with POAG among women.

  View details for Web of Science ID 000321786700003

• Glaucoma severity and medication adherence in a county hospital population. Ophthalmology Ung, C., Zhang, E., Alfaro, T., Murakami, Y., Zhang, M., Seider, M. I., Lin, S. C., Singh, K. 2013; 120 (6): 1150-1157

  Abstract

  To assess the association between disease severity and adherence with glaucoma medications in a county hospital population.Cross-sectional study.A total of 126 patients diagnosed with glaucoma receiving intraocular pressure (IOP)-lowering medication were recruited from the San Francisco General Hospital Ophthalmology Clinic.Subjects completed an oral questionnaire to assess demographic information, knowledge of glaucoma, and perceptions of glaucoma medication adherence. Glaucoma disease severity was classified according to the American Academy of Ophthalmology's Preferred Practice Pattern guidelines. Medication adherence was measured for each patient by obtaining pharmacy refill data and calculating medication possession ratio (MPR), that is, the ratio of total days' supply of medication during a 365-day period. Adherence was measured retrospectively over the 18-month period before study entry. Subjects with an MPR >80% were considered adherent.Medication adherence.Subjects with mild or moderate glaucoma were more likely to be nonadherent to their prescribed glaucoma medications than those with severe disease (adjusted odds ratio [OR], 1.54; 95% confidence interval [CI], 1.03-2.31; P = 0.04). Age, gender, race, education level, years of glaucoma, number of medications, and glaucoma diagnosis were not found to be statistically significantly associated with adherence.Patients with severe glaucoma were more likely to adhere to their topical IOP-lowering medication regimen than those with milder glaucomatous disease.Proprietary or commercial disclosure may be found after the references.

  View details for DOI 10.1016/j.ophtha.2012.11.026

  View details for PubMedID 23453512

• Glaucoma and vitamins A, C, and E supplement intake and serum levels in a population-based sample of the United States EYE Wang, S. Y., Singh, K., Lin, S. C. 2013; 27 (4): 487-494

  Abstract

  To investigate the potential association between glaucoma prevalence and supplemental intake, as well as serum levels of vitamins A, C and E.This cross-sectional study included 2912 participants in the 2005-2006 National Health and Nutrition Examination Survey, age ?40 years, who self-reported a presence or absence of glaucoma. Participants were interviewed regarding the use of dietary supplements during the preceding 30-day period. Participants also underwent serum measurements of vitamins A, C, and E (both alpha- and gamma-tocopherol). Information on the primary outcome measure, presence or absence of glaucoma, as well as demographic information, comorbidities and health-related behaviors, was assessed via interview.Multivariate odds ratios for self-reported glaucoma, comparing the highest quartile of consumption to no consumption, and adjusted for potential confounding variables were 0.48 (95% confidence interval (CI) 0.13-1.82) for vitamin A, 0.47 (95% CI 0.23-0.97) for vitamin C, and 2.59 (95% CI 0.89-7.56) for vitamin E. Adjusted odds ratios for self-reported glaucoma comparing the highest vs lowest quintiles of vitamin serum levels were 1.44 (95% CI 0.79-2.62) for vitamin A, 0.94 (95% CI 0.42-2.11) for vitamin C, 1.40 (95% CI 0.70-2.81) for alpha-tocopherol, and 0.64 (95% CI 0.24-1.70) for gamma-tocopherol.Neither supplementary consumption with nor serum levels of vitamins A and E were found to be associated with glaucoma prevalence. While low- and high-dose supplementary consumption of vitamin C was found to be associated with decreased odds of glaucoma, serum levels of vitamin C did not correlate with glaucoma prevalence.

  View details for DOI 10.1038/eye.2013.10

  View details for Web of Science ID 000317594000005

  View details for PubMedID 23429409

• Myopia and glaucoma: diagnostic and therapeutic challenges CURRENT OPINION IN OPHTHALMOLOGY Chang, R. T., Singh, K. 2013; 24 (2): 96-101

  Abstract

  There is strong epidemiologic evidence linking myopia with glaucomatous disease, but a myopic optic nerve can pose significant challenges with regard to making the correct diagnosis of glaucoma. This review provides an overview of these diagnostic and therapeutic challenges with a particular focus on how the growing prevalence of myopia among specific populations may impact such therapy.For a given individual, the link between myopia and glaucoma remains murky in many circumstances, largely because of the fact that it is difficult to separate out myopia-related structural and functional abnormalities from 'true' glaucomatous changes. Using optical coherence tomography (OCT) imaging, myopia has been found to be associated with temporal displacement and thinning of the superior and inferior nerve fiber layer bundles. In particular, sequential generations of 'Asian' ethnicities have been noted to demonstrate increasing rates of high myopia at earlier ages, sometimes with associated visual field defects at normal intraocular pressures. As is the case with any progressive condition, it is often not possible to distinguish glaucomatous from nonglaucomatous disease based on a single examination, and thus follow-up with OCT or perimetry from an established baseline is useful.Although myopia is a known risk factor for glaucoma, it may also result in structural and functional defects that cannot be distinguished from those caused by glaucoma based solely on cross-sectional information. Longitudinal observation may be necessary to distinguish among the multiple effects of myopia on the optic nerve and the natural history of glaucoma, which may vary substantially amongst those who are affected.

  View details for DOI 10.1097/ICU.0b013e32835cef31

  View details for Web of Science ID 000317039900002

  View details for PubMedID 23542349

• Intravitreal ranibizumab as an adjunct for Ahmed valve surgery in open-angle glaucoma: a pilot study CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY Desai, R. U., Singh, K., Lin, S. C. 2013; 41 (2): 155-158

  Abstract

  To determine the safety and efficacy of intravitreal ranibizumab therapy before and after Ahmed tube insertion for open-angle glaucoma as a means of optimizing postoperative intraocular pressure control.Randomized, controlled trial.Open-angle glaucoma patients scheduled for Ahmed tube insertion, randomized to ranibizumab or control groups.Ranibizumab (0.5 mg in 0.05 mL) was administered intravitreally at three time points: 9 days prior to surgery, 1 month post-surgery and 2 months post-surgery. Control patients underwent the same procedure without ranibizumab.Success at 6 months postoperatively was defined as intraocular pressure <18 mmHg with no adjunctive medications or intraocular pressure <15 mmHg with one adjunctive medication.The study and control arms included six and five subjects, respectively, with four in each arm undergoing combined cataract surgery. In the ranibizumab arm, the preoperative and postoperative intraocular pressure/medication usage was 21.0 ± 6.7 mmHg on 3.2 ± 1.5 medications and 14.7 ± 1.9 mmHg on 0.5 ± 0.8 medications, respectively. In the control arm, preoperative and postoperative intraocular pressure/medication usage was 18.8 ± 3.8 mmHg on 2.8 ± 1.3 medications and 16.2 ± 3.6 mmHg with 1.8 ± 1.6 medications, respectively. Success was achieved in 83% of subjects in the ranibizumab group compared with 40% in the control group (two-tailed Fisher's exact test, P = 0.24).The findings from this small pilot comparative study suggest that intravitreal ranibizumab use may be a safe and potentially effective adjunctive treatment modality in improving success after Ahmed tube placement.

  View details for DOI 10.1111/j.1442-9071.2012.02836.x

  View details for Web of Science ID 000316808300008

  View details for PubMedID 22712537

• CDKN2B-AS1 genotype-glaucoma feature correlations in primary open-angle glaucoma patients from the United States. American journal of ophthalmology Pasquale, L. R., Loomis, S. J., Kang, J. H., Yaspan, B. L., Abdrabou, W., Budenz, D. L., Chen, T. C., DelBono, E., Friedman, D. S., Gaasterland, D., Gaasterland, T., Grosskreutz, C. L., Lee, R. K., Lichter, P. R., Liu, Y., McCarty, C. A., Moroi, S. E., Olson, L. M., Realini, T., Rhee, D. J., Schuman, J. S., Singh, K., Vollrath, D., Wollstein, G., Zack, D. J., Allingham, R. R., Pericak-Vance, M. A., Weinreb, R. N., Zhang, K., Hauser, M. A., Richards, J. E., Haines, J. L., Wiggs, J. L. 2013; 155 (2): 342-353 e5

  Abstract

  To assess the association between single nucleotide polymorphisms (SNPs) of the gene region containing cyclin-dependent kinase inhibitor 2B antisense noncoding RNA (CDKN2B-AS1) and glaucoma features among primary open-angle glaucoma (POAG) patients.Retrospective observational case series.We studied associations between 10 CDKN2B-AS1 SNPs and glaucoma features among 976 POAG cases from the Glaucoma Genes and Environment (GLAUGEN) study and 1971 cases from the National Eye Institute Glaucoma Human Genetics Collaboration (NEIGHBOR) consortium. For each patient, we chose the feature from the eye with the higher value. We created cohort-specific multivariable models for glaucoma features and then meta-analyzed the results.For 9 of the 10 protective CDKN2B-AS1 SNPs with minor alleles associated with reduced disease risk (eg, the G allele at rs2157719), POAG patients carrying these minor alleles had smaller cup-to-disc ratio (0.05 units smaller per G allele at diagnosis; 95% CI: -0.08, -0.03; P = 6.23E-05) despite having higher intraocular pressure (IOP) (0.70 mm Hg higher per G allele at DNA collection; 95% CI: 0.40, 1.00; P = 5.45E-06). For the 1 adverse rs3217992 SNP with minor allele A associated with increased disease risk, POAG patients with A alleles had larger cup-to-disc ratio (0.05 units larger per A allele at diagnosis; 95% CI: 0.02, 0.07; P = 4.74E-04) despite having lower IOP (-0.57 mm Hg per A allele at DNA collection; 95% CI: -0.84, -0.29; P = 6.55E-05).Alleles of CDKN2B-AS1 SNPs, which influence risk of developing POAG, also modulate optic nerve degeneration among POAG patients, underscoring the role of CDKN2B-AS1 in POAG.

  View details for DOI 10.1016/j.ajo.2012.07.023

  View details for PubMedID 23111177

• CDKN2B-AS1 Genotype-Glaucoma Feature Correlations in Primary Open-Angle Glaucoma Patients From the United States AMERICAN JOURNAL OF OPHTHALMOLOGY Pasquale, L. R., Loomis, S. J., Kang, J. H., Yaspan, B. L., Abdrabou, W., Budenz, D. L., Chen, T. C., DelBono, E., Friedman, D. S., Gaasterland, D., Gaasterland, T., Grosskreutz, C. L., Lee, R. K., Lichter, P. R., Liu, Y., McCarty, C. A., Moroi, S. E., Olson, L. M., Realini, T., Rhee, D. J., Schuman, J. S., Singh, K., Vollrath, D., Wollstein, G., Zack, D. J., Allingham, R. R., Pericak-Vance, M. A., Weinreb, R. N., Zhang, K., Hauser, M. A., Richards, J. E., Haines, J. L., Wiggs, J. L. 2013; 155 (2): 342-353

  View details for DOI 10.1016/j.ajo.2012.07.023

  View details for Web of Science ID 000314137400019

• Late Acute Myopia Syndrome Induced by Combination of Sulfonamide Drugs. Journal of glaucoma Kozner, P., Simonova, K., Brozek, B., Singh, K. 2013

  Abstract

  We present a case of late acute myopia syndrome following discontinuation of treatment with a combination of sulphonamide drugs. To the best of our knowledge, this is the first reported case with such a presentation, and suggests that the pathophysiological basis for the acute myopia syndrome is a rapid decrease in serum carbonic anhydrase inhibitors levels which may lead to a rebound increase in the production of aqueous humor and accumulation of suprachoroidal fluid. It is further postulated that there may be a cumulative effect of sulphonamide drug use on carbonic anhydrase activity in the ciliary body epithelium of susceptible individuals.

  View details for PubMedID 23661047

• Association between Myopia and Glaucoma in the United States Population INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Qiu, M., Wang, S. Y., Singh, K., Lin, S. C. 2013; 54 (1): 830-835

  Abstract

  To investigate the association between myopia and the prevalence of glaucoma.This cross-sectional study included 5277 participants from the 2005 to 2008 National Health and Nutrition Examination Survey, greater than or equal to 40 years old, without history of cataract or refractive surgery, who underwent auto-refraction measurement. The predictor was refractive status; emmetropia (-0.99 to +0.99 diopters [D]), mild myopia (-1.00 to -2.99 D), moderate myopia (-3.00 to -5.99 D), severe myopia (> -6.00 D), and hyperopia (> 1.00 D). The outcomes were self-reported glaucoma, vertical cup-to-disc ratio and visual field defects as found on frequency doubling technology (FDT) testingOdds of self-reported glaucoma were not significantly increased in mild (odds ratio [OR] 0.90, confidence interval [CI] 0.56-1.45), moderate (OR 1.40, CI 0.62-3.16), or severe (OR 0.26, CI 0.08-0.80) myopes compared with emmetropes. Odds of vertical cup-to-disc ratio greater than or equal to 0.7 were not significantly increased in mild (OR 0.84, CI 0.31-2.25), moderate (OR 0.37, CI 0.04-3.57), or severe (OR 0.85, CI 0.09-8.42) myopes compared with emmetropes. Odds of any visual field defects were significantly increased in mild (OR 2.02, CI 1.28-3.19), moderate (OR 3.09, CI 1.42-6.72), and severe (OR 14.43, CI 5.13-40.61) myopes compared with emmetropes. The ?(2) test indicated a significant difference (P = 0.001) in the distribution of subjects with each category of visual field status across subjects with each refractive status; the proportion of subjects with worse visual field defects increased with worsening myopia severity.The association between myopia and visual field defects may represent an increased risk of glaucoma among myopes, and the lack of association with self-reported glaucoma may suggest a need for greater glaucoma surveillance in this population.

  View details for DOI 10.1167/iovs.12-11158

  View details for Web of Science ID 000314338400109

  View details for PubMedID 23299483

• Timely cataract surgery for improved glaucoma management JOURNAL OF CATARACT AND REFRACTIVE SURGERY Chang, R. T., Shingleton, B. J., Singh, K. 2012; 38 (10): 1709-1710

  View details for DOI 10.1016/j.jcrs.2012.08.030

  View details for Web of Science ID 000309736500002

  View details for PubMedID 22999597

• PREVALENCE OF DIABETES MELLITUS AND DIABETIC RETINOPATHY IN FILIPINO VS CAUCASIAN AMERICANS: A RETROSPECTIVE CROSS-SECTIONAL EPIDEMIOLOGIC STUDY OF TWO CONVENIENCE SAMPLES ETHNICITY & DISEASE Sales, C. S., Lee, R. Y., Agadzi, A. K., Hee, M. R., Singh, K., Lin, S. C. 2012; 22 (4): 459-465

  Abstract

  To compare the prevalence of diabetic retinopathy in Filipino and Caucasian Americans in two clinic populations.Retrospective cross-sectional epidemiologic study of two convenience samples.Five hundred twelve Filipino and 600 Caucasian patients aged 40 years or older examined by two community-based comprehensive ophthalmology clinics during a one-year period.The prevalence of self-reported type 2 diabetes mellitus among Filipino (F) and Caucasian Americans (C) was 40.6% and 24.8%, respectively (P<.001). In the subpopulation with type 2 diabetes mellitus (n=375: 208 Filipino; 149 Caucasian), there was a statistically insignificant higher prevalence of diabetic retinopathy among Filipino diabetics compared to Caucasians (F vs C: all forms of diabetic retinopathy, 24.5% vs 16.8%, P=.08; non-proliferative retinopathy, 17.3% vs 12.8%, P=.24; proliferative retinopathy, 7.2% vs. 4.0%, P=.21). In multivariate analyses of the diabetic subpopulation, Filipino ethnicity was not a significant predictor of diabetic retinopathy.Filipino Americans may have a higher prevalence of type 2 diabetes mellitus and diabetic retinopathy than Caucasian Americans. Among those with type 2 diabetes, however, Filipino Americans were not found to be more likely to show manifestations of diabetic retinopathy than Caucasian Americans.

  View details for Web of Science ID 000310559400011

  View details for PubMedID 23140077

• Prevalence and Predictors of Depression Among Participants With Glaucoma in a Nationally Representative Population Sample AMERICAN JOURNAL OF OPHTHALMOLOGY Wang, S. Y., Singh, K., Lin, S. C. 2012; 154 (3): 436-444

  Abstract

  To investigate the prevalence of and risk factors for depression among participants with glaucoma and the predictive value of glaucoma for depression.Cross-sectional study.This study included 6760 participants in the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2008, aged ?40 years, who reported a presence or absence of glaucoma. Demographic and disease-related information was obtained by interview. Self-reported measures of vision were ascertained via items from the Visual Function Questionnaire (VFQ-25). Participants underwent visual acuity examination, fundus photography, and visual field testing with screening frequency-doubling technology (FDT N-30-5). The main outcome was presence of depression, as determined by a score ?10 on the Patient Health Questionnaire-9 (PHQ-9).Prevalence of depression among participants with and without glaucoma was 10.9% (SEM 2.2%) and 6.9% (SEM 0.62%), respectively. While the presence of glaucoma was significantly associated with depression after adjustment for demographic factors (OR 1.80, 95% CI 1.16-2.79), this association was not significant after adjustment for self-reported general health condition (OR 1.35, 95% CI 0.822-2.23). Among participants with glaucoma, objective measures of glaucoma severity were not significant predictors for depression. However, several self-reported measures of visual function were significantly associated with depression.Glaucoma is a significant predictor of depression after adjustment for demographic factors and multiple comorbidities, but not after adjustment for self-reported general health condition. Among participants with glaucoma, self-reported measures of vision were significant risk factors for depression, whereas objective measures of vision were not.

  View details for DOI 10.1016/j.ajo.2012.03.039

  View details for Web of Science ID 000308115600005

  View details for PubMedID 22789562

• RAND-like Appropriateness Methodology Consensus for Primary Open-Angle Glaucoma in Latin America AMERICAN JOURNAL OF OPHTHALMOLOGY Fabian Lerner, S., Singh, K., Susanna, R., Wilson, M. R., Lee, B. L., Maul, E. 2012; 154 (3): 460-465

  Abstract

  To report the results of a Latin American consensus panel regarding the diagnosis and management of primary open-angle glaucoma and to compare these results with those from a similar panel in the United States.A RAND-like (Research and Development) appropriateness methodology was used to assess glaucoma practice in Latin America.The 148 polling statements created for the RAND- like analysis in the United States and 10 additional statements specific to glaucoma care in Latin America were presented to a panel of Latin American glaucoma experts. Panelists were polled in private using the RAND- like methodology before and after the panel meeting.Consensus agreement or disagreement among Latin American experts was reached for 51.3% of statements before the meeting and increased to 66.5% in the private, anonymous meeting after polling (79.0% agreement, 21.0% disagreement). Although there was a high degree of concordance (111 of 148 statements; 75%) between the results of this Latin American panel and the United States panel, there were some notable exceptions relating to diagnostic and therapeutic decision making.This RAND-like consensus methodology provides a perspective of how Latin American glaucoma practitioners view many aspects of glaucoma and compares these results with those obtained using a similar methodology from practitioners in the United States. These findings may be helpful to ophthalmologists providing glaucoma care in Latin America and in other regions of the world.

  View details for DOI 10.1016/j.ajo.2012.03.015

  View details for Web of Science ID 000308115600008

  View details for PubMedID 22626620

• Glaucoma surgery with and without cataract surgery: Revolution or evolution? JOURNAL OF CATARACT AND REFRACTIVE SURGERY Choi, D., Suramethakul, P., Lindstrom, R. L., Singh, K. 2012; 38 (7): 1121-1122

  View details for DOI 10.1016/j.jcrs.2012.05.005

  View details for Web of Science ID 000306164200002

  View details for PubMedID 22727279

• Genome-Wide Analysis of Central Corneal Thickness in Primary Open-Angle Glaucoma Cases in the NEIGHBOR and GLAUGEN Consortia INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Ulmer, M., Li, J., Yaspan, B. L., Ozel, A. B., Richards, J. E., Moroi, S. E., Hawthorne, F., Budenz, D. L., Friedman, D. S., Gaasterland, D., Haines, J., Kang, J. H., Lee, R., Lichter, P., Liu, Y., Pasquale, L. R., Pericak-Vance, M., Realini, A., Schuman, J. S., Singh, K., Vollrath, D., Weinreb, R., Wollstein, G., Zack, D. J., Zhang, K., Young, T., Allingham, R. R., Wiggs, J. L., Ashley-Koch, A., Hauser, M. A. 2012; 53 (8): 4468-4474

  Abstract

  To investigate the effects of central corneal thickness (CCT)-associated variants on primary open-angle glaucoma (POAG) risk using single nucleotide polymorphisms (SNP) data from the Glaucoma Genes and Environment (GLAUGEN) and National Eye Institute (NEI) Glaucoma Human Genetics Collaboration (NEIGHBOR) consortia.A replication analysis of previously reported CCT SNPs was performed in a CCT dataset (n = 1117) and these SNPs were then tested for association with POAG using a larger POAG dataset (n = 6470). Then a CCT genome-wide association study (GWAS) was performed. Top SNPs from this analysis were selected and tested for association with POAG. cDNA libraries from fetal and adult brain and ocular tissue samples were generated and used for candidate gene expression analysis.Association with one of 20 previously published CCT SNPs was replicated: rs12447690, near the ZNF469 gene (P = 0.001; ? = -5.08 ?m/allele). None of these SNPs were significantly associated with POAG. In the CCT GWAS, no SNPs reached genome-wide significance. After testing 50 candidate SNPs for association with POAG, one SNP was identified, rs7481514 within the neurotrimin (NTM) gene, that was significantly associated with POAG in a low-tension subset (P = 0.00099; Odds Ratio [OR] = 1.28). Additionally, SNPs in the CNTNAP4 gene showed suggestive association with POAG (top SNP = rs1428758; P = 0.018; OR = 0.84). NTM and CNTNAP4 were shown to be expressed in ocular tissues.The results suggest previously reported CCT loci are not significantly associated with POAG susceptibility. By performing a quantitative analysis of CCT and a subsequent analysis of POAG, SNPs in two cell adhesion molecules, NTM and CNTNAP4, were identified and may increase POAG susceptibility in a subset of cases.

  View details for DOI 10.1167/iovs.12-9784

  View details for Web of Science ID 000307096400018

  View details for PubMedID 22661486

• Dark-light Change of Iris Parameters and Related Factors Among American Caucasians, American Chinese, and Mainland Chinese CURRENT EYE RESEARCH Wang, D., He, M., Wu, L., Kao, A., Pekmezci, M., Singh, K., Lin, S. 2012; 37 (7): 599-605

  Abstract

  To assess the distribution of dark-light changes in iris features and associated factors amongst American Caucasians, American Chinese and mainland Chinese aged 40 years and over.Four gender- and age-matched cohorts: Caucasians, American Chinese, Southern Chinese and Northern Chinese comprised the study population. Anterior segment optical coherence tomography (ASOCT) images were acquired under dark and light conditions. Customized software was used to calculate iris thickness at 750 μm from the scleral spur (IT750), iris curvature (ICurv), iris area (IArea), and pupil diameter (PD) from ASOCT images.Data from 121, 124, 121 and 120 subjects were available for American Caucasian, American Chinese, Southern and Northern Chinese subjects respectively. Caucasians had significantly less dark-light change (Δ) of IT750 and greater ΔPD than Chinese. When using multiple linear regression analyses, the inter-ethnic difference for ΔIT750 was independent of age, gender, refractive error, anterior chamber width and axial length. After controlling for ΔPD, ΔICurv was found to be inversely associated with age (β = -0.001, P = 0.001). Independent predictors of greater ΔPD included younger age (β = -0.02, P = 0.001), Caucasian ethnicity (β = -0.022, P = 0.009) and wider anterior chamber (β = 0.18, P = 0.03).Compared with Caucasians, Chinese irides show greater thickening with light to dark adaptation despite the lesser change of PD in Chinese. The change of iris area per unit change of pupil diameter from dark to light did not differ between ethnicities. These dynamic characteristics intrinsic to Chinese irides may partially account for the substantially increased risk for angle closure among this ethnic group.

  View details for DOI 10.3109/02713683.2012.660593

  View details for Web of Science ID 000305010400007

  View details for PubMedID 22578180

• Author Response: The Association between Glaucoma Prevalence and Supplementation with the Oxidants Calcium and Iron INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Singh, K., Wang, S., Lin, S. 2012; 53 (8): 4940-4940

  View details for DOI 10.1167/iovs.12-10433

  View details for Web of Science ID 000307096400073

• Clinical Characterization of Young Chinese Myopes With Optic Nerve and Visual Field Changes Resembling Glaucoma JOURNAL OF GLAUCOMA Kumar, R. S., Baskaran, M., Singh, K., Aung, T. 2012; 21 (5): 281-286

  Abstract

  To clinically characterize young Chinese myopic patients with optic disc changes suggestive of glaucoma.In this prospective study, patients ?50 years of age who had myopia and suspected glaucomatous optic neuropathy (group A) were compared with established glaucoma patients (group B) and normals (group C). Risk factors such as family history of glaucoma and history of vasospasm and ischemic risk factors were compared. Ophthalmic examination included optic disc assessment and static automated perimetry. Peak diurnal intraocular pressure (IOP) and fluctuation were measured for groups A and C.Ninety-two patients were enrolled (32 patients in group A, 43 in group B, and 21 in group C). Mean refractive error differed between group A [-6.59 Diopter sphere (DS); 95% CI, -8.51 to -4.68] and group B (-0.92 DS; 95% CI, -2.05 to 0.19) (P<0.0001) and C (-0.17 DS; 95% CI, -0.48 to 0.14) (P<0.0001). Optic disc tilt was more common in group A (31.3%) compared with group B (16.3%, P=0.01); both groups had comparable vertical cup-to-disc ratios (P=0.58). The visual field mean pattern standard deviation was higher for group A compared with group B (P=0.03), whereas mean deviation was similar (P=0.42); group A had less frequent hemifield defects (P=0.02). Mean peak diurnal IOP in group A (19.0 mm Hg; 95% CI, 17.3-20.7) was significantly higher than group C (15.8 mm Hg; 95% CI, 14.6-17.0, P=0.007); mean IOP fluctuation showed no difference (P=0.19). Ischemic risk factors were more common in group B compared with A (P<0.0001).Although the clinical features of myopia and glaucoma-like optic nerve changes in young Chinese individuals may allow differentiation from older glaucoma patients of the same ethnicity, such a distinction is not reliable enough to make definitive differential management recommendations for these groups in all circumstances at the present time. A prospective observational study with matching of groups on potentially confounding variables is necessary to better assess and compare the natural history of glaucomatous disease in such groups of patients.

  View details for DOI 10.1097/IJG.0b013e318218253b

  View details for Web of Science ID 000305084100001

  View details for PubMedID 21623224

• Postoperative Complications in the Tube Versus Trabeculectomy (TVT) Study During Five Years of Follow-up AMERICAN JOURNAL OF OPHTHALMOLOGY Gedde, S. J., Herndon, L. W., Brandt, J. D., Budenz, D. L., Feuer, W. J., Schiffman, J. C. 2012; 153 (5): 804-814

  Abstract

  To describe postoperative complications encountered in the Tube Versus Trabeculectomy (TVT) Study during 5 years of follow-up.Multicenter randomized clinical trial.Settings: Seventeen clinical centers. Study Population: Patients 18 to 85 years of age who had previous trabeculectomy and/or cataract extraction with intraocular lens implantation and uncontrolled glaucoma with intraocular pressure (IOP) ?18 mm Hg and ?40 mm Hg on maximum tolerated medical therapy. Interventions: Tube shunt (350-mm(2) Baerveldt glaucoma implant) or trabeculectomy with mitomycin C (MMC 0.4 mg/mL for 4 minutes). Main Outcome Measures: Surgical complications, reoperations for complications, visual acuity, and cataract progression.Early postoperative complications occurred in 22 patients (21%) in the tube group and 39 patients (37%) in the trabeculectomy group (P = .012). Late postoperative complications developed in 36 patients (34%) in the tube group and 38 patients (36%) in the trabeculectomy group during 5 years of follow-up (P = .81). The rate of reoperation for complications was 22% in the tube group and 18% in the trabeculectomy group (P = .29). Cataract extraction was performed in 13 phakic eyes (54%) in the tube group and 9 phakic eyes (43%) in the trabeculectomy group (P = .43).A large number of surgical complications were observed in the TVT Study, but most were transient and self-limited. The incidence of early postoperative complications was higher following trabeculectomy with MMC than tube shunt surgery. The rates of late postoperative complications, reoperation for complications, and cataract extraction were similar with both surgical procedures after 5 years of follow-up.

  View details for DOI 10.1016/j.ajo.2011.10.024

  View details for Web of Science ID 000303964800003

  View details for PubMedID 22244522

• Treatment Outcomes in the Tube Versus Trabeculectomy (TVT) Study After Five Years of Follow-up AMERICAN JOURNAL OF OPHTHALMOLOGY Gedde, S. J., Schiffman, J. C., Feuer, W. J., Herndon, L. W., Brandt, J. D., Budenz, D. L. 2012; 153 (5): 789-803

  Abstract

  To report 5-year treatment outcomes in the Tube Versus Trabeculectomy (TVT) Study.Multicenter randomized clinical trial.Settings: Seventeen clinical centers. Study population: Patients 18 to 85 years of age who had previous trabeculectomy and/or cataract extraction with intraocular lens implantation and uncontrolled glaucoma with intraocular pressure (IOP) ?18 mm Hg and ?40 mm Hg on maximum tolerated medical therapy. Interventions: Tube shunt (350-mm(2) Baerveldt glaucoma implant) or trabeculectomy with mitomycin C ([MMC]; 0.4 mg/mL for 4 minutes). Main outcome measures: IOP, visual acuity, use of supplemental medical therapy, and failure (IOP >21 mm Hg or not reduced by 20%, IOP ?5 mm Hg, reoperation for glaucoma, or loss of light perception vision).A total of 212 eyes of 212 patients were enrolled, including 107 in the tube group and 105 in the trabeculectomy group. At 5 years, IOP (mean ± SD) was 14.4 ± 6.9 mm Hg in the tube group and 12.6 ± 5.9 mm Hg in the trabeculectomy group (P = .12). The number of glaucoma medications (mean ± SD) was 1.4 ± 1.3 in the tube group and 1.2 ± 1.5 in the trabeculectomy group (P = .23). The cumulative probability of failure during 5 years of follow-up was 29.8% in the tube group and 46.9% in the trabeculectomy group (P = .002; hazard ratio = 2.15; 95% confidence interval = 1.30 to 3.56). The rate of reoperation for glaucoma was 9% in the tube group and 29% in the trabeculectomy group (P = .025).Tube shunt surgery had a higher success rate compared to trabeculectomy with MMC during 5 years of follow-up in the TVT Study. Both procedures were associated with similar IOP reduction and use of supplemental medical therapy at 5 years. Additional glaucoma surgery was needed more frequently after trabeculectomy with MMC than tube shunt placement.

  View details for DOI 10.1016/j.ajo.2011.10.026

  View details for Web of Science ID 000303964800002

  View details for PubMedID 22245458

• Long-term effect of phacoemulsification on intraocular pressure using phakic fellow eye as control JOURNAL OF CATARACT AND REFRACTIVE SURGERY Chang, T. C., Budenz, D. L., Liu, A., Kim, W. I., Dang, T., Li, C., Iwach, A. G., Radhakrishnan, S., Singh, K. 2012; 38 (5): 866-870

  Abstract

  To investigate the long-term effect of phacoemulsification on intraocular pressure (IOP) in patients with ocular hypertension and open-angle glaucoma.Three multispecialty ophthalmology practices and one glaucoma specialty group.Retrospective comparative case series.Review of medical records of patients with open-angle glaucoma or ocular hypertension who had had unilateral phacoemulsification (without other prior or concurrent ophthalmic procedure) with the fellow eye remaining phakic at least 3 years postoperatively.Preoperatively, the IOP in the surgical and fellow eyes in the 29 patients was 15.66 mm Hg ± 3.33 (SD) and 15.64 ± 4.23 mm Hg (P=.98), respectively. Postoperatively, it was 13.56 ± 2.04 mm Hg and 14.92 ± 2.85 mm Hg, respectively, at 4.5 months (P=.06); 14.88 ± 3.20 mm Hg and 15.27 ± 3.19 mm Hg, respectively, at 1 year (P=.67); 14.16 ± 2.61 mm Hg and 14.95 ± 2.79 mm Hg, respectively, at 2 years (P=.37); and 14.68 ± 3.44 mm Hg and 14.68 ± 2.68 mm Hg at 3 years (P=1.00), respectively. There was no significant difference in the mean number of IOP-lowering medications used in the surgical eyes (1.96 ± 1.40) and fellow eyes (2.08 ± 1.44) postoperatively (P=.77).In a cohort of ocular hypertensive and glaucoma patients, uncomplicated phacoemulsification had no significant IOP-lowering effect compared with the phakic fellow eye for up to 3 years postoperatively. There was also no difference between the mean number of postoperative IOP-lowering medications used in the surgical and fellow eyes.No author has a financial or proprietary interest in any material or method mentioned.

  View details for DOI 10.1016/j.jcrs.2012.01.016

  View details for Web of Science ID 000303846300020

  View details for PubMedID 22370470

• Common Variants at 9p21 and 8q22 Are Associated with Increased Susceptibility to Optic Nerve Degeneration in Glaucoma PLOS GENETICS Wiggs, J. L., Yapan, B. L., Hauser, M. A., Kane, J. H., Allingham, R. R., Olson, L. M., Abdrabou, W., Fan, B. J., Wang, D. Y., Brodeur, W., Budenz, D. L., Caprioli, J., Crenshaw, A., Crooks, K., DelBono, E., Doheny, K. F., Friedman, D. S., Gaasterland, D., Gaasterland, T., Laurie, C., Lee, R. K., Lichter, P. R., Loomis, S., Liu, Y., Medeiros, F. A., McCarty, C., Mirel, D., Moroi, S. E., Musch, D. C., Realini, A., Rozsa, F. W., Schuman, J. S., Scott, K., Singh, K., Stein, J. D., Trager, E. H., VanVeldhuisen, P., Vollrath, D., Wollstein, G., Yoneyama, S., Zhang, K., Weinreb, R. N., Ernst, J., Kellis, M., Masuda, T., Zack, D., Richards, J. E., Pericak-Vance, M., Pasquale, L. R., Haines, J. L. 2012; 8 (4): 413-424

  Abstract

  Optic nerve degeneration caused by glaucoma is a leading cause of blindness worldwide. Patients affected by the normal-pressure form of glaucoma are more likely to harbor risk alleles for glaucoma-related optic nerve disease. We have performed a meta-analysis of two independent genome-wide association studies for primary open angle glaucoma (POAG) followed by a normal-pressure glaucoma (NPG, defined by intraocular pressure (IOP) less than 22 mmHg) subgroup analysis. The single-nucleotide polymorphisms that showed the most significant associations were tested for association with a second form of glaucoma, exfoliation-syndrome glaucoma. The overall meta-analysis of the GLAUGEN and NEIGHBOR dataset results (3,146 cases and 3,487 controls) identified significant associations between two loci and POAG: the CDKN2BAS region on 9p21 (rs2157719 [G], OR?=?0.69 [95%CI 0.63-0.75], p?=?1.86×10?¹?), and the SIX1/SIX6 region on chromosome 14q23 (rs10483727 [A], OR?=?1.32 [95%CI 1.21-1.43], p?=?3.87×10?¹¹). In sub-group analysis two loci were significantly associated with NPG: 9p21 containing the CDKN2BAS gene (rs2157719 [G], OR?=?0.58 [95% CI 0.50-0.67], p?=?1.17×10?¹²) and a probable regulatory region on 8q22 (rs284489 [G], OR?=?0.62 [95% CI 0.53-0.72], p?=?8.88×10?¹?). Both NPG loci were also nominally associated with a second type of glaucoma, exfoliation syndrome glaucoma (rs2157719 [G], OR?=?0.59 [95% CI 0.41-0.87], p?=?0.004 and rs284489 [G], OR?=?0.76 [95% CI 0.54-1.06], p?=?0.021), suggesting that these loci might contribute more generally to optic nerve degeneration in glaucoma. Because both loci influence transforming growth factor beta (TGF-beta) signaling, we performed a genomic pathway analysis that showed an association between the TGF-beta pathway and NPG (permuted p?=?0.009). These results suggest that neuro-protective therapies targeting TGF-beta signaling could be effective for multiple forms of glaucoma.

  View details for DOI 10.1371/journal.pgen.1002654

  View details for Web of Science ID 000303441800031

  View details for PubMedID 22570617

• The Tube Versus Trabeculectomy Study: interpretation of results and application to clinical practice CURRENT OPINION IN OPHTHALMOLOGY Gedde, S. J., Singh, K., Schiffman, J. C., Feuer, W. J. 2012; 23 (2): 118-126

  Abstract

  The Tube Versus Trabeculectomy (TVT) Study is a multicenter randomized clinical trial comparing the safety and efficacy of tube-shunt surgery to trabeculectomy with mitomycin C (MMC) in eyes with previous cataract and/or failed glaucoma surgery. This article interprets results from the TVT Study and applies them to clinical practice.Both tube-shunt surgery and trabeculectomy with MMC produced intraocular pressure (IOP) reduction to the low teens throughout the 5-year duration of the study. Tube-shunt surgery was associated with use of more glaucoma medications than trabeculectomy with MMC during the first 2 years of the study, but medical therapy equalized with longer follow-up. Trabeculectomy with MMC had higher rates of surgical failure and reoperation for glaucoma compared with tube-shunt surgery. Vision loss occurred at a similar rate with the two surgical procedures. Early complications were more frequent after trabeculectomy with MMC relative to tube-shunt surgery, but both procedures had similar rates of late postoperative complications and serious complications.Tube-shunt surgery and trabeculectomy with MMC are both viable surgical options for managing glaucoma in patients who have undergone prior cataract and/or failed filtering surgery. Results of the TVT Study support the expanding use of tube shunts beyond refractory glaucomas.

  View details for DOI 10.1097/ICU.0b013e32834ff2d1

  View details for Web of Science ID 000300455400006

  View details for PubMedID 22249235

• Differences in iris structural measurements among American Caucasians, American Chinese and mainland Chinese CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY Wang, D., He, M., Wu, L., Yaplee, S., Singh, K., Lin, S. 2012; 40 (2): 162-169

  Abstract

  To assess the distribution of iris structural measurements among American Caucasians, American Chinese and mainland Chinese aged 40years and over, in order to determine associated factors of increased risk for angle closure in Chinese.Prospective multicentre cross-sectional study.Four gender- and age-matched cohorts: Caucasians, American Chinese, Southern Chinese from Guangzhou and Northern Chinese from Beijing were enrolled in this study.Anterior segment optical coherence tomography was utilized to image the anterior chamber. Customized software was used to calculate the related parameters from anterior segment optical coherence tomography images.Iris thickness at 750µm from the scleral spur, iris curvature, iris area, pupil diameter.Data from 121, 124, 121 and 120 subjects were available for American Caucasian, American Chinese, Southern and Northern Mainland Chinese subjects, respectively. The Chinese cohorts did not differ with regard to any of the parameters. Multiple linear regressions indicated that Caucasians had thinner iris thickness at 750µm from the scleral spur and smaller iris area than Chinese after controlling for potential confounders. Female Caucasians had thinner irides (P=0.015) and smaller iris area (P=0.001) than male Caucasians. Female Chinese tended to have more convex irides (P=0.021) than male Chinese. Pupil size was inversely associated with age (P<0.001) in both ethnicities.In dark conditions, Chinese have thicker irides and greater iris area than Caucasians independent of pupil size. Among Chinese, more convex irides in women may account for the higher rate of narrow angles identified in this segment of the Chinese population.

  View details for DOI 10.1111/j.1442-9071.2011.02658.x

  View details for Web of Science ID 000301533200009

  View details for PubMedID 21794048

• The Association between Glaucoma Prevalence and Supplementation with the Oxidants Calcium and Iron INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Wang, S. Y., Singh, K., Lin, S. C. 2012; 53 (2): 725-731

  Abstract

  To investigate the relationship between supplementary consumption of the oxidants calcium and iron and the prevalence of glaucoma.This cross-sectional study included 3833 participants in the National Health and Nutrition Examination Survey (NHANES) for 2007 and 2008, ? 40 years of age, who reported a presence or absence of glaucoma. Participants were interviewed regarding the use of dietary supplements and antacids during the preceding 30-day period. Data pertaining to the supplementary intake of calcium and iron was aggregated and divided into quintiles. Information regarding the presence or absence of glaucoma and demographics, comorbidities, and health-related behavior was obtained via interview.Participants who consumed ? 800 mg/d of supplementary calcium or ? 18 mg/d of supplementary iron had significantly higher odds of having been diagnosed with glaucoma than did those who had not consumed supplementary calcium or iron, after adjustment for potential confounders (odds ratio [OR] 2.44, 95% confidence interval [CI] 1.25-4.76 for calcium; OR 3.80, 95% CI 1.79-8.06 for iron). Concurrent consumption of both calcium and iron above these levels was associated with still greater odds of having been diagnosed with glaucoma (OR 7.24, 95% CI 2.42-21.62). A clear dose-response relationship between quintiles of supplementary calcium or iron intake and glaucoma prevalence was not found.These results suggest that there may be a threshold intake of iron and calcium above which there is an increased risk of development of glaucoma. Prospective longitudinal studies are needed, to assess whether oxidant intake is a risk factor for development and progression of glaucoma.

  View details for DOI 10.1167/iovs.11-9038

  View details for Web of Science ID 000302788600024

  View details for PubMedID 22247455

• Laser Trabeculoplasty for Open-Angle Glaucoma OPHTHALMOLOGY Samples, J. R., Singh, K., Lin, S. C., Francis, B. A., Hodapp, E., Jampel, H. D., Smith, S. D. 2011; 118 (11): 2296-2302

  Abstract

  To provide an evidence-based summary of the outcomes, repeatability, and safety of laser trabeculoplasty for open-angle glaucoma.A search of the peer-reviewed literature in the PubMed and the Cochrane Library databases was conducted in June 2008 and was last repeated in March 2010 with no date or language restrictions. The search yielded 637 unique citations, of which 145 were considered to be of possible clinical relevance for further review and were included in the evidence analysis.Level I evidence indicates an acceptable long-term efficacy of initial argon laser trabeculoplasty for open-angle glaucoma compared with initial medical treatment. Among the remaining studies, level II evidence supports the efficacy of selective laser trabeculoplasty for lowering intraocular pressure for patients with open-angle glaucoma. Level III evidence supports the efficacy of repeat use of laser trabeculoplasty.Laser trabeculoplasty is successful in lowering intraocular pressure for patients with open-angle glaucoma. At this time, there is no literature establishing the superiority of any particular form of laser trabeculoplasty. The theories of action of laser trabeculoplasty are not elucidated fully. Further research into the differences among the lasers used in trabeculoplasty, the repeatability of the procedure, and techniques of treatment is necessary.Proprietary or commercial disclosure may be found after the references.

  View details for DOI 10.1016/j.ophtha.2011.04.037

  View details for Web of Science ID 000296573500027

  View details for PubMedID 21849211

• Intraocular Pressure Variability and Glaucoma Risk Complex and Controversial ARCHIVES OF OPHTHALMOLOGY Singh, K., Sit, A. J. 2011; 129 (8): 1080-1081

  View details for DOI 10.1001/archophthalmol.2011.66

  View details for Web of Science ID 000293648800017

  View details for PubMedID 21482856

• Novel Glaucoma Procedures A Report by the American Academy of Ophthalmology OPHTHALMOLOGY Francis, B. A., Singh, K., Lin, S. C., Hodapp, E., Jampel, H. D., Samples, J. R., Smith, S. D. 2011; 118 (7): 1466-1480

  Abstract

  To review the published literature and summarize clinically relevant information about novel, or emerging, surgical techniques for the treatment of open-angle glaucoma and to describe the devices and procedures in proper context of the appropriate patient population, theoretic effects, advantages, and disadvantages.Devices and procedures that have US Food and Drug Administration clearance or are currently in phase III clinical trials in the United States are included: the Fugo blade (Medisurg Ltd., Norristown, PA), Ex-PRESS mini glaucoma shunt (Alcon, Inc., Hunenberg, Switzerland), SOLX Gold Shunt (SOLX Ltd., Boston, MA), excimer laser trabeculotomy (AIDA, Glautec AG, Nurnberg, Germany), canaloplasty (iScience Interventional Corp., Menlo Park, CA), trabeculotomy by internal approach (Trabectome, NeoMedix, Inc., Tustin, CA), and trabecular micro-bypass stent (iStent, Glaukos Corporation, Laguna Hills, CA).Literature searches of the PubMed and the Cochrane Library databases were conducted up to October 2009 with no date or language restrictions.These searches retrieved 192 citations, of which 23 were deemed topically relevant and rated for quality of evidence by the panel methodologist. All studies but one, which was rated as level II evidence, were rated as level III evidence.All of the devices studied showed a statistically significant reduction in intraocular pressure and, in some cases, glaucoma medication use. The success and failure definitions varied among studies, as did the calculated rates. Various types and rates of complications were reported depending on the surgical technique. On the basis of the review of the literature and mechanism of action, the authors also summarized theoretic advantages and disadvantages of each surgery.The novel glaucoma surgeries studied all show some promise as alternative treatments to lower intraocular pressure in the treatment of open-angle glaucoma. It is not possible to conclude whether these novel procedures are superior, equal to, or inferior to surgery such as trabeculectomy or to one another. The studies provide the basis for future comparative or randomized trials of existing glaucoma surgical techniques and other novel procedures.

  View details for DOI 10.1016/j.ophtha.2011.03.028

  View details for Web of Science ID 000292303000035

  View details for PubMedID 21724045

• Central corneal thickness and related factors in an elderly American Chinese population CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY Wang, D., Singh, K., Weinreb, R., Kempen, J., He, M., Lin, S. 2011; 39 (5): 412-420

  Abstract

  To assess central corneal thickness and related factors in an elderly American Chinese population residing in San Francisco.Cross-sectional community based study.American Chinese aged 40 years and older were enrolled using random cluster sampling and volunteer screening in the Chinatown district of San Francisco.The following data were obtained: central corneal thickness by ultrasound pachymetry, intraocular pressure by Goldmann applanation tonometry, axial length by A-scan biometry, refractive status and corneal curvature by autorefractor. History of systemic and ocular diseases was collected via standard questionnaire.Central corneal thickness.Of 311 eligible subjects, 274 consented to study participation, and 228 phakic eyes were analyzed. Mean corneal thickness was 524.1 ± 31.1 µm, 545.5 ± 30.9 µm and 538.9 ± 31.8 µm in the sampling cluster, volunteer group and all subjects, respectively. A multiple linear regression model showed corneal thickness to be negatively associated with age (standardized regression coefficient [SRC] = -0.21; P = 0.016) and corneal curvature (SRC = -0.19; P = 0.018) but positively correlated with intraocular pressure (SRC = 0.20; P = 0.023).The distribution of central corneal thickness among this American Chinese population is similar to that reported in studies from East Asia. The independent factors associated with thinner corneas included older age, lower intraocular pressure and greater corneal curvature. While descendents of Chinese immigrants in America have, on average, thicker corneas than their ancestors, this phenomenon is potentially impacted by the level of intraocular pressure.

  View details for DOI 10.1111/j.1442-9071.2010.02472.x

  View details for Web of Science ID 000292650600007

  View details for PubMedID 21105973

• Racial and Ethnic Disparities in Adherence to Glaucoma Follow-up Visits in a County Hospital Population ARCHIVES OF OPHTHALMOLOGY Murakami, Y., Lee, B. W., Duncan, M., Kao, A., Huang, J., Singh, K., Lin, S. C. 2011; 129 (7): 872-878

  Abstract

  To identify predictors of inconsistent attendance at glaucoma follow-up visits in a county hospital population.Prospective recruitment from August 1, 2008, through January 31, 2009, of 152 individuals with glaucoma, with 1-to-1 matching of patients (those with inconsistent follow-up) and controls (those with consistent follow-up). Data were collected via oral questionnaire. Survey results were correlated with attendance at follow-up examinations, using the t test, ?(2) test, and multivariate stepwise logistic regression analysis to calculate the odds ratios (ORs) and 95% confidence intervals.After adjusting for covariates in the logistic regression analysis, factors independently associated with inconsistent follow-up included black race (adjusted OR, 7.16; 95% confidence interval, 1.64-31.24), Latino ethnicity (adjusted OR, 4.77; 1.12-20.29), unfamiliarity with necessary treatment duration (adjusted OR, 3.54; 1.26-9.94), lack of knowledge of the permanency of glaucoma-induced vision loss (adjusted OR, 3.09; 1.18-8.04), and perception that it is not important to attend all follow-up visits (adjusted OR, 3.54; 1.26-9.94).Demographic factors, including race and ethnicity, may directly or indirectly affect adherence to recommended glaucoma follow-up visits. Lack of information regarding irreversible vision loss from glaucoma, need for lifelong treatment, and lack of visual symptoms may be significant barriers to follow-up in this population. Targeted glaucoma education by physicians may improve follow-up, thereby decreasing the morbidity associated with glaucomatous disease.

  View details for Web of Science ID 000292604000005

  View details for PubMedID 21746977

• Interpretation and misinterpretation of results from the tube versus trabeculectomy study. International ophthalmology clinics Singh, K., Gedde, S. J. 2011; 51 (3): 141-154

  View details for DOI 10.1097/IIO.0b013e31821e542e

  View details for PubMedID 21633244

• Assessment of Visual Function in Glaucoma A Report by the American Academy of Ophthalmology OPHTHALMOLOGY Jampel, H. D., Singh, K., Lin, S. C., Chen, T. C., Francis, B. A., Hodapp, E., Samples, J. R., Smith, S. D., Collins, N. 2011; 118 (5): 986-1002

  Abstract

  To review the published literature to summarize and evaluate the effectiveness of visual function tests in diagnosing glaucoma and in monitoring progression.Literature searches of the PubMed and Cochrane Library databases were conducted last on May 7, 2010, and were restricted to citations published on or after January 1, 1994. The search yielded 1063 unique citations. The first author reviewed the titles and abstracts of these articles and selected 185 of possible clinical relevance for further review. The panel members reviewed the full text of these articles and determined that 85 met inclusion criteria. They conducted data abstraction of the 85 studies, and the panel methodologist assigned a level of evidence to each of the selected articles. One study was rated as level I evidence. The remaining articles were classified broadly as providing level II evidence. Studies deemed to provide level III evidence were not included in the assessment.Standard white-on-white automated perimetry remains the most commonly performed test for assessing the visual field, with the Swedish interactive threshold algorithm (SITA) largely replacing full-threshold testing strategies. Frequency-doubling technology and its refinement into Matrix perimetry, as well as short-wavelength automated perimetry, now available with SITA, have been evaluated extensively. Machine learning classifiers seem to be ready for incorporation into software to help distinguish glaucomatous from nonglaucomatous fields. Other technologies, such as multifocal visual-evoked potential and electroretinography, which were designed as objective measures of visual function, provide testing free of patient input, but issues prevent their adoption for glaucoma management.Advances in technology and analytic tools over the past decade have provided us with more rapid and varied ways of assessing visual function in glaucoma, but they have yet to produce definitive guidance on the diagnosis of glaucoma or its progression over time. Further research on an objective measure of visual function is needed.

  View details for DOI 10.1016/j.ophtha.2011.03.019

  View details for Web of Science ID 000290090300030

• Treatment Outcomes in the Ahmed Baerveldt Comparison Study after 1 Year of Follow-up OPHTHALMOLOGY Budenz, D. L., Barton, K., Feuer, W. J., Schiffman, J., Costa, V. P., Godfrey, D. G., Buys, Y. M. 2011; 118 (3): 443-452

  Abstract

  To determine the relative efficacy and complications of the Ahmed glaucoma valve (AGV) model FP7 (New World Medical, Ranchos Cucamonga, CA) and the Baerveldt glaucoma implant (BGI) model 101-350 (Abbott Medical Optics, Abbott Park, IL) in refractory glaucoma.Multicenter, randomized, controlled clinical trial.Two hundred seventy-six patients, including 143 in the AGV group and 133 in the BGI group.Patients 18 to 85 years of age with refractory glaucoma having intraocular pressure (IOP) of 18 mmHg or more in whom an aqueous shunt was planned were randomized to undergo implantation of either an AGV or a BGI.The primary outcome was failure, defined as IOP >21 mmHg or not reduced by 20% from baseline, IOP ?5 mmHg, reoperation for glaucoma or removal of implant, or loss of light perception vision. Secondary outcomes included mean IOP, visual acuity, use of supplemental medical therapy, and complications.Preoperative IOP (mean±standard deviation [SD]) was 31.2±11.2 mmHg in the AGV group and 31.8±12.5 mmHg in the BGI group (P = 0.71). At 1 year, mean±SD IOP was 15.4±5.5 mmHg in the AGV group and 13.2±6.8 mmHg in the BGI group (P = 0.007). The mean±SD number of glaucoma medications was 1.8±1.3 in the AGV group and 1.5±1.4 in the BGI group (P = 0.071). The cumulative probability of failure was 16.4% (standard error [SE], 3.1%) in the AGV group and 14.0% (SE, 3.1%) in the BGI group at 1 year (P = 0.52). More patients experienced early postoperative complications in the BGI group (n = 77; 58%) compared with the AGV group (n = 61; 43%; P = 0.016). Serious postoperative complications associated with reoperation, vision loss of ?2 Snellen lines, or both occurred in 29 patients (20%) in the AGV group and in 45 patients (34%) in the BGI group (P = 0.014).Although the average IOP after 1 year was slightly higher in patients who received an AGV, there were fewer early and serious postoperative complications associated with the use of the AGV than the BGI.

  View details for DOI 10.1016/j.ophtha.2010.07.016

  View details for Web of Science ID 000287964400004

  View details for PubMedID 20932583

• The Ahmed Baerveldt Comparison Study Methodology, Baseline Patient Characteristics, and Intraoperative Complications OPHTHALMOLOGY Barton, K., Gedde, S. J., Budenz, D. L., Feuer, W. J., Schiffman, J. 2011; 118 (3): 435-442

  Abstract

  The Ahmed Baerveldt Comparison (ABC) Study compares the long-term outcomes and complications of the Ahmed glaucoma valve (AGV; model FP7; New World Medical, Los Ranchos, CA) and the Baerveldt glaucoma implant (BGI; model 101-350; Abbott Medical Optics, Abbott Park, IL).Multicenter, randomized, controlled clinical trial.Two hundred seventy-six glaucoma patients at 16 clinical centers worldwide who were 18 to 85 years of age with inadequately controlled intraocular pressure (IOP; ?18 mmHg) in whom placement of an aqueous shunt was planned.Study patients were randomized to undergo implantation of an AGV or a BGI.Failure, defined as IOP >21 mmHg or not reduced by 20% less than baseline or IOP ?5 mmHg (2 consecutive visits after 3 months), additional glaucoma surgery, removal of the implant, or loss of light perception vision.A total of 276 patients were enrolled between October 2006 and April 2008, including 143 in the AGV group and 133 in the BGI group. The mean age±standard deviation (SD) of patients enrolled was 63±14 years, and 52% were male. The mean baseline IOP±SD was 31.5±11.8 mmHg. Except for a 13% higher prevalence of hypertension in the AGV group, no significant differences in baseline demographic or ocular characteristics were observed between the study groups. Intraoperative complications occurred in 11 (8%) patients in the AGV group and in 16 (12%) patients in the BGI group (P = 0.31).The ABC Study should yield valuable prospective data comparing 2 commonly used aqueous shunts in clinical practice.

  View details for DOI 10.1016/j.ophtha.2010.07.015

  View details for Web of Science ID 000287964400003

  View details for PubMedID 20932581

• Medical management of glaucoma: principles and practice. Indian journal of ophthalmology Singh, K., Shrivastava, A. 2011; 59: S88-92

  Abstract

  Glaucoma care is more an art than science. The introduction of several new classes of glaucoma medications and the completion of many large randomized clinical trials have not changed this fact. While we now have better choices when initiating glaucoma therapy relative to our predecessors, the principles of glaucoma therapy have not changed much during this period. Debates continue regarding the utility of concepts such as "the monocular therapeutic trial," "target intraocular pressure (IOP)," and "maximal medical therapy." Our tools for detecting and following glaucomatous disease have improved but are not precise enough for us to prospectively predict which patients will do better or worse than others. Much attention has been given to disease stage, rate of progression, and compliance with medications but regular patient follow-up, an area that has received little attention, may be among the most important predictors of patient outcomes.

  View details for DOI 10.4103/0301-4738.73691

  View details for PubMedID 21150040

• Medical management of glaucoma: Principles and practice INDIAN JOURNAL OF OPHTHALMOLOGY Singh, K., Shrivastava, A. 2011; 59: S88-S92

  View details for DOI 10.4103/0301-4738.73691

  View details for Web of Science ID 000208741900014

• Axial Length Does Not Correlate With Degree of Visual Field Loss in Myopic Chinese Individuals With Glaucomatous Appearing Optic Nerves JOURNAL OF GLAUCOMA Chao, D. L., Shrivastava, A., Kim, D. H., Lin, H., Singh, K. 2010; 19 (8): 509-513

  Abstract

  We previously described a group of patients of Chinese ancestry who presented with optic nerve appearance and visual field loss suggestive of glaucoma but did not show progression characteristic of this disease for up to 7 years. The purpose of this study was to assess whether axial length is a risk factor for visual field loss in patients presenting with this cluster of findings.Twenty patients of Chinese ancestry with characteristics of this previously described condition including myopia, tilted discs, and glaucomatous visual field abnormalities who also had asymmetric visual field loss were enrolled in this study. Patients underwent axial length measurement of both eyes and a fellow eye analysis was performed to determine the relationship between axial length and visual field loss.Tilted discs were found in 30 out of 40 eyes, with cup/disc ratios ranging from 0.5 to 0.9. Myopia >6.00 diopters was also found in 30 out of 40 eyes. In these subjects with disease that was discordant between the 2 eyes, longer axial length was not found to be associated with greater visual field loss (P>0.99, Freeman-Halton extension of the Fisher exact test). No correlation was found between axial length and mean deviation on visual field testing (r=-0.06).We did not find axial length to be a risk factor for visual field loss in eyes with asymmetric disease in this patient population. These findings suggest that factors other than progressive lengthening of the eye play an important role in the etiology of glaucomatous appearing optic nerve damage and visual field loss in this specific subset of patients.

  View details for DOI 10.1097/IJG.0b013e3181d12dae

  View details for Web of Science ID 000282986300003

  View details for PubMedID 20179621

• Spontaneous Venous Pulsation as a Barometer for Translaminar Pressure Fluctuation JOURNAL OF GLAUCOMA Chang, T. C., Singh, K. 2010; 19 (5): 347-348

  View details for DOI 10.1097/IJG.0b013e3181c29b3f

  View details for Web of Science ID 000279006300015

  View details for PubMedID 20543631

• The effect of cataract extraction on intraocular pressure CURRENT OPINION IN OPHTHALMOLOGY Shrivastava, A., Singh, K. 2010; 21 (2): 118-122

  Abstract

  To review the current ophthalmic literature regarding the impact of modern cataract surgery on intraocular pressure (IOP).Many articles in the literature demonstrate a modest, long-lasting decrease in IOP following phacoemulsification and posterior chamber intraocular lens implantation in patients with primary open-angle glaucoma and ocular hypertension. The mechanism of this average pressure-lowering effect has yet to be elucidated. The IOP reductions obtained in patients with angle closure glaucoma are often more pronounced than those seen in patients with open angles. Patients with higher levels of preoperative IOP obtain greater average reductions in IOP, although this phenomenon may partially be explained by a statistical effect known as regression to the mean.Although it is well recognized that phacoemulsification may result in a modest sustained reduction in IOP, there are several limitations in the studies that have assessed the magnitude of this effect. The implications of such IOP reduction with cataract surgery on the medical and surgical algorithms for care in patients with open-angle glaucoma and coexistent cataract remain unclear. In contrast, the substantial benefits of cataract surgery in patients with acute and chronic angle-closure glaucoma have been well studied and are generally widely accepted. An improved understanding of the pathophysiological mechanisms of IOP lowering after cataract extraction may help us better predict which patients are most likely to benefit from simple cataract extraction, obviating the need for combined cataract and glaucoma surgical procedures in such circumstances.

  View details for DOI 10.1097/ICU.0b013e3283360ac3

  View details for Web of Science ID 000275063500005

  View details for PubMedID 20040874

• Review of results from the Tube Versus Trabeculectomy Study CURRENT OPINION IN OPHTHALMOLOGY Gedde, S. J., Heuer, D. K., Parrish, R. K. 2010; 21 (2): 123-128

  Abstract

  The Tube Versus Trabeculectomy (TVT) Study is a multicenter randomized clinical trial comparing the safety and efficacy of tube-shunt surgery to trabeculectomy with mitomycin (MMC) in eyes with previous cataract and/or unsuccessful glaucoma surgery. This article reviews published results from the TVT Study.Tube-shunt surgery had a higher success rate than trabeculectomy with MMC during the first 3 years of follow-up. Trabeculectomy with MMC produced greater intraocular pressure (IOP) reduction in the early postoperative period compared with tube-shunt placement, but similar IOPs were observed after 3 months. Tube-shunt surgery was associated with greater use of adjunctive-medical therapy than trabeculectomy with MMC during the first 2 years of the study, but no difference in medication use was seen at 3 years. The incidence of postoperative complications was higher after trabeculectomy with MMC compared with tube-shunt surgery, but serious complications associated with vision loss and/or reoperation developed with similar frequency after both surgical procedures. No difference in the rate of vision loss was present following trabeculectomy with MMC and tube-shunt surgery after 3 years of follow-up. Cataract progression was common, but occurred with similar frequency with both procedures.Intermediate-term results of the TVT Study support the expanded use of tube shunts beyond refractory glaucomas. Tube-shunt surgery is an appropriate surgical option in patients who have undergone prior cataract and/or unsuccessful filtering surgery.

  View details for DOI 10.1097/ICU.0b013e3283360b68

  View details for Web of Science ID 000275063500006

  View details for PubMedID 20040872

• Postfiltration Hypotony Maculopathy in Young Chinese Myopic Women With Glaucomatous Appearing Optic Neuropathy JOURNAL OF GLAUCOMA Silva, R. A., Doshi, A., Law, S. K., Singh, K. 2010; 19 (2): 105-110

  Abstract

  To describe management and surgical outcomes of 3 young women of Chinese origin with advanced glaucomatous optic neuropathy.Three 36 to 48-year-old female patients.A retrospective medical records review of 3 Chinese women with prior diagnoses of glaucoma treated with trabeculectomy was performed. Optic nerve imaging and standard automated perimetry were also reviewed. Mean follow-up period was 4 years.All patients had arcuate scotomas bilaterally at the time of initial ophthalmic examination. Two patients were highly myopic (>or= -6.00 diopter spherical equivalent) with tilting of the optic nerve head and parapapillary atrophy. Cup-to-disc ratios ranged from 0.4 to 0.9. Trabeculectomy with mitomycin C was performed in the right eye of all patients with subsequent hypotony related complications requiring surgical treatment. All patients experienced long-term decline in best-corrected visual acuity after trabeculectomy. No patient had a new area of field loss on standard automated perimetry, although the density of the preexisting scotomas increased in the nonoperated eye of all patients.High myopia, optic nerve head tilting, and parapapillary atrophy are likely associated with the increased susceptibility to damage of dependent axons. Axons outside of the area of tilt may be relatively protected. As young myopes are more likely to suffer from hypotony related complications after trabeculectomy, the risk of an increase in preexisting field defect density should be weighed against the risk of long-term vision loss after filtration surgery. The development of a new area of field loss may be an appropriate indication for surgery in some such patients.

  View details for DOI 10.1097/IJG.0b013e3181a98a39

  View details for Web of Science ID 000274915500006

  View details for PubMedID 19661828

• Three-Year Follow-up of the Tube Versus Trabeculectomy Study AMERICAN JOURNAL OF OPHTHALMOLOGY Gedde, S. J., Schiffman, J. C., Feuer, W. J., Herndon, L. W., Brandt, J. D., Budenz, D. L. 2009; 148 (5): 670-684

  Abstract

  To report 3-year results of the Tube Versus Trabeculectomy (TVT) Study.Multicenter randomized clinical trial.Seventeen clinical centers.Patients 18 to 85 years of age who had previous trabeculectomy, cataract extraction with intraocular lens implantation, or both and uncontrolled glaucoma with intraocular pressure (IOP) > or =18 mm Hg and < or =40 mm Hg on maximum tolerated medical therapy.A 350-mm(2) Baerveldt glaucoma implant or trabeculectomy with mitomycin C (MMC 0.4 mg/ml for 4 minutes).IOP, visual acuity, use of supplemental medical therapy, surgical complications, and failure (IOP >21 mm Hg or not reduced by 20%, IOP < or =5 mm Hg, reoperation for glaucoma, or loss of light perception vision).A total of 212 eyes of 212 patients were enrolled, including 107 in the tube group and 105 in the trabeculectomy group. At 3 years, IOP (mean +/- standard deviation [SD]) was 13.0 +/- 4.9 mm Hg in the tube group and 13.3 +/- 6.8 mm Hg in the trabeculectomy group (P = .78). The number of glaucoma medications (mean +/- SD) was 1.3 +/- 1.3 in the tube group and 1.0 +/- 1.5 in the trabeculectomy group (P = .30). The cumulative probability of failure during the first 3 years of follow-up was 15.1% in the tube group and 30.7% in the trabeculectomy group (P = .010; hazards ratio, 2.2; 95% confidence interval, 1.2 to 4.1). Postoperative complications developed in 42 patients (39%) in the tube group and 63 patients (60%) in the trabeculectomy group (P = .004). Surgical complications were associated with reoperation and/or loss of > or =2 Snellen lines in 24 patients (22%) in the tube group and 28 patients (27%) in the trabeculectomy group (P = .58).Tube shunt surgery had a higher success rate compared to trabeculectomy with MMC during the first 3 years of follow-up in the TVT Study. Both procedures were associated with similar IOP reduction and use of supplemental medical therapy at 3 years. While the incidence of postoperative complications was higher following trabeculectomy with MMC relative to tube shunt surgery, most complications were transient and self-limited.

  View details for DOI 10.1016/j.ajo.2009.06.018

  View details for Web of Science ID 000271669300008

  View details for PubMedID 19674729

• Intraocular pressure fluctuations: how much do they matter? CURRENT OPINION IN OPHTHALMOLOGY Singh, K., Shrivastava, A. 2009; 20 (2): 84-87

  Abstract

  To review the current literature with regard to the importance of IOP fluctuation/variation as independent risk factors for glaucoma progression.There are conflicting reports in the literature assessing the relative importance of 'intraocular pressure (IOP) fluctuation' and 'mean IOP' as risk factors for glaucoma progression. There has been a trend toward more studies concluding that IOP fluctuation is an important independent risk factor for such progression but there is considerable variability in the quality of such studies. In particular, assumptions regarding causality have created doubt regarding some conclusions. Recent studies have also suggested that we should not abandon mean IOP as the important predictor of glaucoma progression. It should be noted that several analyses pertaining to this subject have emerged from large prospective randomized clinical trials primarily designed to answer other questions.A review of the literature reveals that there is no conclusive evidence that IOP fluctuation/variation are independent risk factors for glaucoma progression. One should not discount the importance of mean IOP as a predictor of such progression. A major factor limiting all analyses pertaining to this issue is the inability to continuously measure IOP and thus optimally assess mean and variability.

  View details for DOI 10.1097/ICU.0b013e328324e6c4

  View details for Web of Science ID 000264201900003

  View details for PubMedID 19248311

• Motility Disturbances in the Tube Versus Trabeculectomy Study During the First Year of Follow-up AMERICAN JOURNAL OF OPHTHALMOLOGY Rauscher, F. M., Gedde, S. J., Schiffman, J. C., Feuer, W. J., Barton, K., Lee, R. K. 2009; 147 (3): 458-466

  Abstract

  To describe the preoperative and postoperative motility disturbances encountered in the Tube Versus Trabeculectomy (TVT) Study during the first year of follow-up.Multicenter randomized clinical trial.settings: Seventeen clinical centers. population: Patients 18 to 85 years old who had previous trabeculectomy and/or cataract surgery and uncontrolled glaucoma with intraocular pressure > or =18 mm Hg and < or =40 mm Hg on maximum tolerated medical therapy. interventions: 350-mm(2) Baerveldt glaucoma implant or trabeculectomy with mitomycin C (MMC). main outcome measures: Preoperative and postoperative evaluation of ocular motility and diplopia.Motility disturbances were detected in 55 patients (28%) at baseline. New-onset persistent diplopia was reported in 5 patients (5%) in the tube group and no patients in the trabeculectomy group at 1 year (P = .06). A new postoperative motility disturbance developed or worsened in 7 patients (9.9%) in the tube group and no patients in the trabeculectomy group during the first year of follow-up (P = .005). Postoperative motility disturbances were also associated with increasing age (P < .001) and right eye surgery (P = .044).Preoperative motility disturbances were common among patients in the TVT Study. New postoperative motility disturbances were more frequent following tube shunt surgery than trabeculectomy with MMC after 1 year of follow-up.

  View details for DOI 10.1016/j.ajo.2008.09.019

  View details for Web of Science ID 000263659000017

  View details for PubMedID 19038375

• Glaucomatous Disease in Patients With Normal Pressure Hydrocephalus JOURNAL OF GLAUCOMA Chang, T. C., Singh, K. 2009; 18 (3): 243-246

  Abstract

  To investigate the relative prevalence of glaucomatous disease in patients with normal pressure hydrocephalus (NPH) compared with age-matched non-NPH controls with hydrocephalus.Case-control study.Using International Classification of Diseases (ICD-9) codes, we identified the medical records of 72 NPH cases and 72 age-matched controls with hydrocephalus treated at Stanford University Hospital between 1996 and 2007.All available electronic medical records were reviewed. The diagnosis of NPH was verified based on clinical presentation, neuroimaging results, and opening pressure on initial access to cerebrospinal fluid space. Glaucoma status was determined based on history and prior medical, laser, or surgical intraocular pressure-lowering therapy.The proportion of subjects determined as having glaucomatous disease in cases and controls.The prevalence of glaucoma in NPH cases was estimated to be 18.1% in contrast to 5.6% in controls (chi=5.403, P=0.0201). The average age of NPH cases and non-NPH controls was 75.40+/-13.4 and 73.96+/-9.92 years (mean+/-SD), respectively.We found the prevalence of a glaucoma diagnosis to be 3-fold greater in patients with NPH as compared with age-matched non-NPH controls with hydrocephalus. These findings suggest the possiblity of an association between these 2 neurodegenerative diseases which should be studied prospectively.

  View details for Web of Science ID 000264408400016

  View details for PubMedID 19295381

• Intraocular Pressure: Does it Measure Up? The open ophthalmology journal Wilson, M. R., Singh, K. 2009; 3: 32-37

  Abstract

  The relationship between intraocular pressure (IOP) and glaucoma is complex and not fully understood. We question the validity of several claims relating to the IOP-glaucoma relationship: (1) that 12 mm Hg is an important target in IOP control; (2) that IOP variability is an important risk factor for glaucoma progression; and (3) that every millimeter of mercury of IOP lowering reduces the risk of glaucoma progression by some specific percentage amount. Further, IOP is generally accepted to be an important - if not most important - risk factor for glaucoma development and progression. Using measures of treatment effect - absolute risk reduction, relative risk, and relative risk reduction - we compare the strength of IOP as a risk factor to the strength of a cardiac risk factor in cardiovascular disease.

  View details for DOI 10.2174/1874364100903020032

  View details for PubMedID 19812717

• Is the patient getting worse? The open ophthalmology journal Singh, K. 2009; 3: 65-66

  Abstract

  Glaucoma care today is often simplified into all or nothing terms with the assumption that if the patient's intraocular pressure (IOP) is above a certain level, glaucomatous disease will progress and when the IOP is lowered to below a threshold, no further progression will occur. This dogma is largely the result of limitations in the resolution of tools currently available to judge progression. Glaucoma is a neurodegenerative disease and, as with all degenerative diseases, progression continues to occur, albeit at slower rates, with appropriate treatment. In the future, as our tools to assess structural and functional optic nerve change become more precise, we will no longer think of glaucoma as being stable or progressive but rather speak in terms of rates of progression.

  View details for DOI 10.2174/1874364100903020065

  View details for PubMedID 19834562

• Early Aggressive Intraocular Pressure Lowering, Target Intraocular Pressure, and a Novel Concept for Glaucoma Care SURVEY OF OPHTHALMOLOGY Singh, K., Shrivastava, A. 2008; 53: S33-S38

  Abstract

  Early diagnosis of glaucomatous optic nerve damage offers the potential for early treatment which may prevent vision loss from this neurodegenerative disease. Even in patients who do not begin early treatment, early diagnosis allows for better monitoring of disease at a stage where the stakes are lower relative to later stages of the disease. For these reasons, early diagnosis of glaucomatous optic nerve disease is desirable and opens the door for appropriately aggressive therapy. The target intraocular pressure (IOP) concept is widely employed by glaucoma practitioners. Although there have been no randomized clinical trials or other high-quality studies showing the benefits of setting a target IOP versus not using this approach, there is ample evidence that lowering IOP slows glaucoma progression and, in general, lower is better, regardless of disease stage and baseline IOP level. We propose an alternative approach to managing glaucoma without the use of the target IOP concept and suggest that this market IOP concept should be compared with the target IOP approach in an appropriately powered comparative clinical trial.

  View details for DOI 10.1016/j.survophthal.2008.08.007

  View details for Web of Science ID 000261587400005

  View details for PubMedID 19038622

• Long-term Comparison of Primary Trabeculectomy With 5-Fluorouracil Versus Mitomycin C in West Africa JOURNAL OF GLAUCOMA Kim, H. Y., Egbert, P. R., Singh, K. 2008; 17 (7): 578-583

  Abstract

  To compare the long-term efficacy and safety of intraoperative 5-fluorouracil (5-FU) versus mitomycin-C (MMC) used adjunctively with primary trabeculectomy in a Black West African population.Retrospective comparative study supplemented with cross-sectional follow-up data.Review of 68 eyes of 68 Black West African subjects that underwent primary trabeculectomy with the use of intraoperative 5-FU or MMC between January 1, 1988 and January 1, 2002 and had at least 3 years postoperative follow-up. Postoperative outcome measures included intraocular pressure (IOP) control, number of glaucoma medications, visual acuity, and complications.Thirty-eight of sixty-eight eyes received 5-FU and 30 received MMC. Mean postoperative follow-up was 7.5 and 6.5 years in the 5-FU and MMC groups, respectively (P=0.17). A higher proportion of eyes in the MMC group achieved "qualified" (with or without medical therapy) success with varying IOP targets relative to the 5-FU group, but the differences were not statistically significant. "Complete" (without medical therapy) postoperative success was greater in the MMC group with a significantly higher proportion achieving an IOP <21 mm Hg (P=0.02). MMC use was also associated with a lower likelihood of receiving IOP-lowering medications postoperatively (P=0.01). Baseline demographic characteristics, preoperative and postoperative IOP, visual acuity, and complications did not differ significantly between the 2 groups.Intraoperative MMC use is associated with a lower likelihood of requiring postoperative medications and a greater likelihood of achieving IOP lowering without medications relative to the use of 5-FU in a Black West African population.

  View details for Web of Science ID 000260317800013

  View details for PubMedID 18854737

• Predictors of and barriers associated with poor follow-up in patients with glaucoma in South India ARCHIVES OF OPHTHALMOLOGY Lee, B. W., Sathyam, P., John, R. K., Singh, K., Robin, A. L. 2008; 126 (10): 1448-1454

  Abstract

  To determine predictors of and reasons for poor longitudinal glaucoma follow-up in South India.This 1-to-1, matched, case-control study enrolled 300 patients with established glaucoma. We defined cases (poor follow-up) and controls (good follow-up) based on number of and maximum interval between glaucoma follow-up visits attended in the preceding year. We collected data by oral questionnaire and used stepwise multivariate logistic regression to calculate odds ratios (ORs) for poor follow-up.Adjusting for age and sex, independent predictors of poor follow-up included lack of formal education (adjusted OR, 4.13; 95% confidence interval [CI], 1.44-11.90), no use of prescribed glaucoma medications (adjusted OR, 2.17; 95% CI, 1.06-4.43), and belief that follow-up is less important if one uses glaucoma medications and has no noticeable visual changes (adjusted OR, 10.59; 95% CI, 3.74-29.97). Age, sex, and disease severity were not significant predictors. The most prevalent barriers to follow-up were belief that there was no problem with one's eyes (44.4%) and lack of escort (19.7%).Knowing predictors of poor follow-up can help identify patients who need individualized strategies to improve follow-up. Because believing one's eyes are problem-free and lacking escorts are significant barriers to follow-up, novel strategies in patient education (eg, intensive counseling, audiovisual aides, and patient support groups) and escort provision may improve longitudinal glaucoma follow-up and disease management.

  View details for Web of Science ID 000259900700017

  View details for PubMedID 18852425

• Prospective comparison of topical moxifloxacin in eliminating conjunctival bacterial flora following a one-day or one-hour application JOURNAL OF OCULAR PHARMACOLOGY AND THERAPEUTICS Ta, C. N., Chan, I., Dhatt, H. S., Paterno, J., Fisher, E., Singh, K., Montague, A., Egbert, P. R., Cockerham, G., de Kaspar, H. M. 2008; 24 (4): 427-431

  Abstract

  The aim of this study was to compare the efficacy of a 1-hour(h) versus 1-day application of topical moxifloxacin in eliminating conjunctival bacterial flora.In this prospective, nonrandomized, controlled trial, the surgical eyes of 60 patients scheduled for intraocular surgery received topical moxifloxacin four times a day, starting 1 day prior to surgery and three additional applications at 5-minute intervals 1 h before surgery. The nonsurgical eye of each patient only received three applications of the same antibiotic at 5-minute intervals 1 h before surgery. Conjunctival cultures were obtained at baseline and after antibiotic application.Prior to antibiotic application, 80% of surgical eyes and 70% of nonsurgical eyes had positive cultures. Following the 1-day application, significantly fewer eyes (40%) had positive cultures (P < 0.0001), with a further reduction to 32% with three additional doses 1 h prior to surgery. In the nonsurgical eye, the decrease in the percentage of positive cultures, from 55% to 53% following the three applications 1 h prior to surgery, was not significant (P > 0.9999). The 1-day application was associated with significantly fewer positive cultures, compared to the 1-h group (P = 0.0267).The one-day application of moxifloxacin resulted in significantly fewer positive conjunctival cultures, compared with a 1-h application.

  View details for DOI 10.1089/jop.2008.0018

  View details for Web of Science ID 000258731100011

  View details for PubMedID 18665815

• A panel assessment of glaucoma management: Modification of existing RAND-like methodology for consensus in ophthalmology. Part II: Results and interpretation AMERICAN JOURNAL OF OPHTHALMOLOGY Singh, K., Lee, B. L., Wilson, M. R. 2008; 145 (3): 575-581

  Abstract

  To present the results of a panel consensus assessment of evaluation and therapy relating to primary open-angle glaucoma based on available evidence and expert opinion.A panel consensus assessment of glaucoma diagnosis and therapy using a modified RAND-like appropriateness methodology.One hundred and forty-eight questions, most of which related to glaucoma therapy, were created by a core nonvoting executive committee based on common clinical questions. An evidence-based review of the literature pertaining to these questions was provided to 10 voting panelists. These panelists, who did not participate in either the creation of the questions or the conduct of the literature review, then were polled using a modified technique derived from existing methodology.Consensus agreement or disagreement was reached for 55.4% and 74.3% of the polling statements before and after the panel meeting, respectively. This represents a consensus agreement or disagreement on a majority of polling statements both before and after a meeting of all panelists and the two co-chairs of the program. There was an increase in the proportion of statements where consensus agreement was reached after the panel meeting.Given the paucity of high-quality evidence relating to many of the issues addressed in this assessment and the variability of practice patterns among ophthalmologists, consensus agreement or disagreement was reached for a high proportion of polling statements.

  View details for DOI 10.1016/j.ajo.2007.10.009

  View details for Web of Science ID 000253841900029

  View details for PubMedID 18191098

• A panel assessment of glaucoma management: Modification of existing RAND-like methodology for consensus in ophthalmology. Part I: Methodology and design AMERICAN JOURNAL OF OPHTHALMOLOGY Wilson, M. R., Lee, P. P., Weinreb, R. N., Lee, B. L., Singh, K. 2008; 145 (3): 570-574

  Abstract

  To examine ways to improve existing methodology to reach appropriate consensus in the treatment of primary open-angle glaucoma.Evidence-based literature and accumulated expert opinion.A core nonvoting steering committee composed of four individuals created 148 statements. Another nonvoting individual with expertise in clinical epidemiology reviewed all evidence in support of or against each statement and summarized this information. After review of these summaries, 10 panelists voted on each of the statements both before and after a panel meeting where each question was discussed by the panel. The polling was conducted online using a customized software program for the process.Consensus was reached on most statements both before and after the panel meeting. The proportion of questions where consensus agreement or disagreement was reached increased from 82 of 148 before the panel meeting to 110 of 148 after the meeting. Detailed information regarding the results of the polling are provided in the accompanying article.(1)Refinements to existing descriptions of modified RAND-like appropriateness methodology was successful in allowing a group of ophthalmology panelists to reach consensus for or against most statements developed by nonpanelists. Future studies should be conducted to compare how robust and valid this methodology is as compared with other methods of determining optimal clinical care decision making.

  View details for DOI 10.1016/j.ajo.2007.10.019

  View details for Web of Science ID 000253841900028

  View details for PubMedID 18191095

• Aqueous Shunts in Glaucoma: a report by the American Accademy of Ophthalmology Ophthalmology Minckler DS, Francis BA, Hodapp EA, Jampel HD, Lin SL, Samples JR, Smith S, Singh K 2008; 115 (6): 1089-98
• Early Aggressive Intraocular Pressure Lowering, Target Intraocular Pressure and a Novel Concept for Glaucoma Care Survey of Ophthalmology Singh K, Shrivastava A. 2008; 53 (1): S33-38
• An Expert Panel Assessment of Glaucoma Therapy: Modification of Existing RAND-Like Methodology for Consensus in Ophthalmology. Part I: Methodology and Design American Journal of Ophthalmology Wilson MR, Lee P, Weinreb RN, Lee B, Singh K, the Glaucoma Modified RAND-Like Methodology Group 2008; 145 (3): 570-574
• Normal Tension Glaucoma: A Different Disease? Journal of Current Glaucoma Practice Singh, K. 2008; 2 (3): 1-3
• Prospective Comparative Evaluation of Povidone-Iodine (10% for 5 minutes versus 5% for 1 minute) as Prophylaxis For Ophthalmic Surgery J. Cataract and Refract Surg Ta CN, Egbert PR, Singh K, Miño De Kaspar H 2008; 34 (1): 171-172
• Comparison of One-Day Versus One-Hour Application of Topical Gatifloxacin in Eliminating Conjunctival Bacterial Flora Ophthalmology Moss MJ, Nguyen D, Liu IY, Singh K, Montague A, Egbert RP, De Kaspar MH, Ta NC 2008; 115 (11): 2013-2016
• Comparison of the ocular hypotensive efficacy of adjunctive brimonidine 0.15% or brinzolamide 1% in combination with travoprost 0.004% OPHTHALMOLOGY Feldman, R. M., Tanna, A. P., Gross, R. L., Chuang, A. Z., Baker, L., Reynolds, A., Prager, T. C. 2007; 114 (7): 1248-1254

  Abstract

  To compare efficacies of adjunctive therapy with brimonidine 0.15% and adjunctive therapy with brinzolamide 1% in combination with travoprost 0.004%.Three-month randomized, parallel-group, double-masked, multicenter clinical trial.Patients with primary open-angle glaucoma, exfoliation glaucoma, or ocular hypertension with intraocular pressure (IOP) > 18 mmHg on monotherapy with travoprost (N = 163).Patients were randomized to receive adjunctive therapy with twice-daily brimonidine (N = 79) or twice-daily brinzolamide (N = 84). Treatment efficacy was assessed after 1 and 3 months of combination therapy. Intraocular pressure was measured at 8 am, noon, and 4 pm at baseline (on travoprost monotherapy) and after 3 months of combination therapy. Mean diurnal IOP was defined as the average of the IOP measurements at these 3 time points. Adverse events were recorded at each visit.Difference between treatment groups in mean diurnal IOP at month 3, adjusted for difference in baseline IOP, using analysis of covariance.Mean diurnal IOPs (+/- standard error of the mean) at baseline were 21.7+/-0.33 mmHg in the brimonidine group and 21.1+/-0.29 mmHg in the brinzolamide group (P = 0.16). Mean diurnal IOPs at month 3 were 19.6+/-0.41 mmHg in the brimonidine group and 18.4+/-0.33 mm Hg in the brinzolamide group (P = 0.019). At month 3, mean diurnal IOPs, adjusted for difference in baseline IOP, were 19.3+/-0.27 in the brimonidine group and 18.6+/-0.25 in the brinzolamide group (P = 0.035).The combination of travoprost and brinzolamide was statistically significantly more efficacious than the combination of travoprost and brimonidine in lowering IOP. The clinical significance of this difference is uncertain.

  View details for DOI 10.1016/j.ophtha.2007.03.012

  View details for Web of Science ID 000247629700003

  View details for PubMedID 17509688

• Nonprogressive glaucomatous cupping and visual field abnormalities in young Chinese males OPHTHALMOLOGY Doshi, A., Kreidl, K. O., Lombardi, L., Sakamoto, D. K., Singh, K. 2007; 114 (3): 472-479

  Abstract

  To describe a series of young to middle-aged men of Chinese origin who presented with a constellation of ocular findings suggestive of glaucoma, that were found to be stable over a 7-year period.Retrospective case series.Sixteen 25- to 66-year-old male patients.Medical records of the participants, of Chinese origin and referred for glaucoma evaluation over a 7-year period, were reviewed. All patients underwent complete ophthalmic examinations, stereo imaging of the optic nerves, and automated perimetry. Fewer than 5% of all patients seen in this practice were of Chinese origin. The patients were observed for the duration of the study in a single glaucoma clinic.Visual field (VF) changes or progressive optic nerve cupping suggestive of glaucoma.The patients had an average age of 38.9 years. Tilted discs were present in 75.0% (24/32) and peripapillary atrophy in 81.3% (26/32) of nerves. Cup-to-disc ratios ranged from 0.20 to 0.95 and averaged 0.56. The lowest intraocular pressure (IOP) in any patient at any time was 8 mmHg, whereas the highest was 29 (average range, 13.5-17.9). Intraocular pressure-lowering therapy had been used in 56.3% (9/16). There was a family history of presumed glaucoma in 25.0% (4/16) of patients. High myopia (>-6.00-diopter spherical equivalent [SE]) was present in 43.8% of eyes (14/32), and SEs ranged from -11.25 to +0.25. The most common VF defect was an arcuate defect, found in 31.3% (10/32) of patients. There were no females of Chinese origin with similar findings identified during this period. Neither optic nerve nor significant VF progression was found during the follow-up period, regardless of the use of IOP-lowering therapy.These young Chinese patients previously diagnosed with glaucoma or considered glaucoma suspects had stable ocular findings for up to 7 years, irrespective of IOP-lowering therapy. Their condition was associated with myopia and tilted discs. Many were being treated with IOP-lowering therapy for glaucoma, a condition they may not have had. Further prospective epidemiologic study is needed to determine whether such a constellation of nonprogressive findings is more common in young Chinese males than in the general population.

  View details for DOI 10.1016/j.ophtha.2006.07.036

  View details for Web of Science ID 000244532800013

  View details for PubMedID 17123617

• Cost-effective evaluation of the glaucoma suspect CURRENT OPINION IN OPHTHALMOLOGY Doshi, A., Singh, K. 2007; 18 (2): 97-103

  Abstract

  The number of glaucoma patients nationwide will increase appreciably over the coming years reflecting the increased number of elderly people. This increase will require efficient allocation of available healthcare resources for management of the entire spectrum of disease from glaucoma suspect to advanced glaucoma. This review considers the cost-effective management of glaucoma suspects.Medications account for the majority of costs of managing glaucoma suspects while the cost of clinical evaluations has remained stable. Early disease recognition limits both direct and indirect costs. Risk stratification of glaucoma suspects can identify those who would benefit most from therapy. Newer structural modalities can be as predictive of early disease progression as stereo disk photography. Short-wavelength automated perimetry and frequency doubling technology may be more appropriate in confirming field changes in this patient population.Overall costs of managing glaucoma can be limited by preventing early disease progression. Identification and monitoring of glaucoma suspects would help minimize overall costs if intraocular pressure lowering therapy is reserved for high-risk glaucoma suspects or those with early disease. Yet, since the rate of progression to blindness for a particular patient is not known, the most cost-effective time to begin intraocular pressure lowering therapy remains unclear.

  View details for Web of Science ID 000244444000001

  View details for PubMedID 17301609

• Optic Nerve Head and Retinal Nerve Fiber Layer Analysis Ophthalmology Lin SL, Singh K, Dueker DK, Fechtner RD, Minckler DS, Samples JR, Schuman JS 2007; 114 (10): 1937-1949
• Criteria for Choosing Clinically Effective Glaucoma Treatment Current Therapeutic Research Thygeson J, Burk R, Carassa R, Crichton A, Goni FJ, Menage M, Miglior S, Montgomery D, Nordmann JP, Roberts T, Singh K 2007; 68 (3)
• Long-Term IOP Fluctuation May Not Be As Important As Previously Reported International Glaucoma Review Singh, K. 2007; 9 (1)
• Treatment Outcomes in the Tube vs Trabeculectomy Study After One Year of Follow-Up American Journal of Ophthalmology Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL, the Tube Versus Trabeculectomy Study Gr 2007; 143 (1): 9-22
• Corneal Thickness Measurement in the Management of Primary Open Angle Glaucoma. Ophthalmology Dueker DK, Singh K, Fechtner RD, Lin SL, Minckler DS, Samples JR, Schuman JS 2007; 114 (9): 1779-1787
• Surgical Complications in the Tube vs Trabeculectomy Study During the First Year of Follow-Up American Journal of Ophthalmology Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC, the Tube Versus Trabeculectomy Study Group 2007; 143 (1): 23-31
• A Blink at Diagnosing Glaucoma Suggests that More May Be Less Ophthalmology Singh K, Van Buskirk EM, Spaeth G 2007; 114 (7): 1239-1240
• Prospective randomized comparison of 2 different methods of 5% povidone-iodine applications for anterior segment intraocular surgery. Archives of ophthalmology Miño de Kaspar, H., Chang, R. T., Singh, K., Egbert, P. R., Blumenkranz, M. S., Ta, C. N. 2005; 123 (2): 161-165

  Abstract

  To determine the efficacy of reducing conjunctival bacteria flora with 2 different regimens of 5% povidone-iodine application: 2 drops on the conjunctiva cul-de-sac vs a 10-mL conjunctival irrigation of the fornices.In this prospective controlled trial, 200 eyes undergoing anterior segment intraocular surgery were randomized to control and study groups. All patients from both groups received topical ofloxacin and a povidone-iodine scrub of the periorbital area before the surgical procedure. The eyes in the control group received 2 drops of povidone-iodine on the conjunctiva preoperatively, whereas eyes in the study group had irrigation of the fornices with 10 mL of povidone-iodine. Conjunctival cultures were obtained at 4 separate time points before and after surgery.Twenty (26%) of 78 eyes in the study group had positive conjunctival cultures immediately prior to surgery compared with 40 (43%) of 94 eyes in the control group (P = .02). At the conclusion of the surgery, 14 (18%) of 78 eyes and 30 (32%) of 94 eyes had positive cultures in the study and control groups, respectively (P = .05).Irrigation of the fornices with 5% povidone-iodine was associated with significantly fewer positive conjunctival cultures at the time of surgery compared with the application of 2 drops on the conjunctiva.

  View details for PubMedID 15710810

• Prospective Randomized Comparison of 2 Different Methods of 5% Povidone-Iodine Applications for Anterior Segment Intraocular Surgery Archives of Ophthalmolology de Kaspar H, Chang RT, Singh K, Egbert PR, Blumenkranz MS, Ta CN 2005; 123 (2): 161-5
• The Tube Versus Trabeculectomy Study: Design and Baseline Characteristics of Study Patients American Journal of Ophthalmology Gedde SJ, Schiffman JC, Feuer WJ, Parrish RK 2nd, Heuer DK, Brandt JD, Tube Versus Trabeculectomy Study Group 2005; 140 (2): 275-87
• Comparison of preoperative conjunctival bacterial flora in patients undergoing glaucoma or cataract surgery JOURNAL OF GLAUCOMA de Kaspar, H. M., Kreidl, K. O., Singh, K., Ta, C. N. 2004; 13 (6): 507-509

  Abstract

  To assess differences in conjunctival bacterial flora between patients undergoing glaucoma and cataract surgery.A prospective study comparing conjunctival bacterial cultures obtained from 339 patients undergoing either cataract (n = 258) or glaucoma (n = 81) surgery. All cultures were acquired during the preoperative visit, approximately three to seven days prior to surgery. The culture samples were inoculated onto blood and chocolate agar, as well as blood culture broth media. All bacterial isolates were identified and statistical analyses were performed to determine if there were differences in flora between the eyes undergoing cataract versus glaucoma surgery.Two hundred fifteen of 258 eyes (83%) undergoing cataract surgery were found to have positive bacterial growth, compared with 62 of 81 eyes (77%) of those undergoing glaucoma surgery (P = 0.2246). Coagulase-negative Staphylococci, the most common bacterial isolate, was cultured from 167 eyes (65%) in the cataract group and 42 (52%) in the glaucoma group (P = 0.0514). Among all bacterial isolates, only Corynebacterium species was found to be statistically different between the two patient groups with 92 (36%) and 11 (14%) eyes testing positive in the cataract and glaucoma groups, respectively (P = 0.0003).There was no statistically significant difference in the proportion of conjunctival culture samples testing positive for bacterial growth in eyes undergoing glaucoma surgery compared with those undergoing cataract surgery. Glaucoma medications, or their preservatives, do not appear to significantly alter conjunctival flora. Techniques used for endophthalmitis prophylaxis prior to cataract surgery are likely appropriate for glaucoma surgery as well.

  View details for Web of Science ID 000225273300014

  View details for PubMedID 15534478

• Three-day application of topical ofloxacin reduces the contamination rate of microsurgical knives in cataract surgery - A prospective randomized study OPHTHALMOLOGY de Kaspar, H. M., Chang, R. T., Shriver, E. M., Singh, K., Egbert, P. R., Blumenkranz, M. S., Ta, C. N. 2004; 111 (7): 1352-1355

  Abstract

  To determine the rate of contamination of microsurgical knives during cataract surgery and the benefit of a 3-day versus a 1-hour preoperative application of topical ofloxacin in reducing the contamination rate.Prospective, randomized controlled trial.Seventy-eight eyes of 75 patients were randomly assigned to control (39 eyes) or study groups (39 eyes).All patients from both groups received 0.3% topical ofloxacin 1 hour before surgery, 5% povidone-iodine (PVI) scrub of the periorbital area, and 2 drops of PVI onto the ocular surface preoperatively. The patients in the study group also received ofloxacin 4 times a day for 3 days before surgery.Microsurgical knives were placed in blood culture broth media immediately after the incision had been made. The number of positive cultures and types of bacteria isolated were determined.Ten of 39 knives (26%) in the control group were found to be positive for bacterial growth compared with only 2 of 39 (5%) in the study group (P = 0.028).The initial paracentesis incision frequently results in contamination of the microsurgical knife and may serve as a mechanism for introducing bacteria from the ocular surface into the anterior chamber. The application of topical ofloxacin for 3 days before surgery significantly reduces the contamination rate of the microsurgical knives, compared with a preoperative application of ofloxacin given 1 hour before surgery.

  View details for Web of Science ID 000222418900017

  View details for PubMedID 15234136

• Update on antifibrotic use in glaucoma surgery, including use in trabeculectomy and glaucoma drainage implants and combined cataract and glaucoma surgery. Current opinion in ophthalmology Yoon, P. S., Singh, K. 2004; 15 (2): 141-146

  Abstract

  This paper summarizes the use of antifibrotic agents adjunctive to glaucoma surgery, reviews recently published studies that address current use of these antifibrotics, and reviews new methods of wound modulation.The use of antifibrotic agents, namely, 5-fluorouracil and mitomycin C, in conjunction with glaucoma surgery has resulted in lower postoperative intraocular pressures after trabeculectomy or combined cataract and glaucoma surgery. Mixed results have been seen when these agents are used with glaucoma drainage device surgery. The use of antifibrotic agents has also created and increased complications. Therefore, methods of antifibrotic use have become more refined and modified for specific circumstances. Promising new wound modulation agents, such as CAT-152, are currently under study.Antifibrotics are potent adjuncts to glaucoma surgery, but along with their beneficial use are risks that need to be considered. While we continue to look for more efficacious agents and methods to treat glaucoma, we must continue to modify techniques with the individual patient's best interest in mind.

  View details for PubMedID 15021227

• A prospective comparison of patient preference with two topical timolol preparations Haw, W., Byrd, S., Singh, K., Tran, T. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2004: U677-U677

  View details for Web of Science ID 000223338202741

• Nonprogressive glaucomatous cupping and visual field abnormalities in young Chinese males Kreidl, K. O., Lombardi, L., Singh, K. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2004: U678-U678

  View details for Web of Science ID 000223338202749

• The challenge of determining aqueous contamination rate in anterior segment intraocular surgery AMERICAN JOURNAL OF OPHTHALMOLOGY Ta, C. N., Egbert, P. R., Singh, K., Blumenkranz, M. S., de Kaspar, H. M. 2004; 137 (4): 662-667

  Abstract

  To determine aqueous contamination rate in anterior segment intraocular surgery using two different techniques of obtaining aqueous fluid and to assess whether a 3-day application of topical 0.3% ofloxacin reduces this contamination rate compared with a 1-hour application.Randomized clinical trial.One hundred and thirty-three eyes of 130 patients undergoing anterior segment intraocular surgery were randomized to either control (64 eyes received topical ofloxacin 1 hour before surgery) or study groups (69 eyes received topical ofloxacin four times a day for 3 days before surgery in addition to 1 hour preoperatively). Eyes in both groups received a periorbital iodine scrub and two drops of topical 5% iodine. Aqueous fluid was obtained at the beginning and conclusion of surgery using a cannula passed through a paracentesis or a needle passed through clear cornea. The aqueous, cannula, and needles were inoculated in blood culture media broth and bacterial growth was identified.Overall, eight of 89 aqueous samples (9%) obtained using a cannula at the beginning of surgery were culture-positive. Similarly, six of 41 aqueous samples (15%) obtained through a needle through clear cornea at the beginning of surgery showed contamination. At the conclusion of surgery, nine of 112 samples (8%) showed positive cultures. There was no difference in the aqueous contamination rates between the control and study groups.Despite the use of a needle to obtain aqueous fluid at the beginning of surgery before creating a paracentesis, the aqueous contamination rate remained higher than that found at the conclusion of surgery. A 3-day application of topical ofloxacin before surgery did not reduce the anterior chamber aqueous contamination rate relative to a 1-hour application.

  View details for DOI 10.1016/j.ajo.2003.11.057

  View details for Web of Science ID 000220762800009

  View details for PubMedID 15059705

• Risk Assessment in the Management of Patients With Ocular Hypertension American Journal of Ophthalmology Weinreb RN, Friedman DS, Fechtner RD, Cioffi GA, Coleman AL, Girkin CA, Liebmann JM, Singh K, Wilson MR, Wilson R, Kannel WB 2004; 138 (3): 458-467
• Applying an Evidence-based Approach to the Management of Patients With Ocular Hypertension: Evaluating and Synthesizing Published Evidence American Journal of Ophthalmology Coleman AL, Singh K, Wilson R, Cioffi GA, Friedman DS, Weinreb RN 2004; 138 (S): 3-10
• The Randomized Clinical Trial: Beware of Limitations Journal of Glaucoma Singh K 2004; 13 (2): 87-89
• Dense pigmentation of the posterior lens capsule associated with the pigment dispersion syndrome JOURNAL OF GLAUCOMA Lin, D. Y., Volpicelli, M., Singh, K. 2003; 12 (6): 491-493

  Abstract

  To report an unusual case of pigment dispersion syndrome associated with unilateral dense pigmentation of the posterior lens capsule.Case report.A 59-year-old male with bilateral pigment dispersion syndrome presented with progressive decrease in visual acuity in the left eye over the past 10 to 20 years. Clinical examination revealed the typical findings of pigment dispersion syndrome including the presence of bilateral Krunkenberg spindles, iris transillumination defects, and heavy trabecular meshwork pigmentation. Of note, there was remarkably dense pigmentation of the posterior lens capsule in the eye with decreased visual acuity.Pigmentation of the posterior lens capsule may be a rare finding associated with pigment dispersion syndrome. Such a finding suggests that there may be aqueous flow into the retrolental space in some patients with this condition. The optimal treatment of this unusual condition remains undetermined.

  View details for Web of Science ID 000186877400009

  View details for PubMedID 14646685

• Antibiotic resistance patterns of ocular bacterial flora - A prospective study of patients undergoing anterior segment surgery OPHTHALMOLOGY Ta, C. N., Chang, R. T., Singh, K., Egbert, P. R., Shriver, E. M., Blumenkranz, M. S., de Kaspar, H. M. 2003; 110 (10): 1946-1951

  Abstract

  To determine the antibiotic susceptibility patterns of conjunctival bacterial flora isolated preoperatively from patients undergoing anterior segment surgery.Prospective observational study.One hundred fifty-six eyes from 139 patients scheduled for anterior segment surgery were enrolled over a 6-month period from August 2001 to February 2002.Conjunctival cultures were obtained on the day of surgery before povidone-iodine or antibiotic application.Bacterial isolates were identified and tested for antibiotic susceptibility using the Kirby-Bauer disc-diffusion technique.Among the 156 eyes studied, 36 were from patients who had undergone either bilateral surgery or more than one surgery in the same eye. Only the first eyes of the 120 patients that underwent initial ocular surgery were included in our analysis. Of these 120 eyes, 21 (18%) showed no bacterial growth. Of the 143 bacterial strains isolated from the remaining 99 eyes, 112 (78%) were coagulase-negative staphylococci (CNS). Among the CNS, greater than 90% were susceptible to cefotaxime, levofloxacin, imipenem, meropenem, vancomycin, and each of the aminoglycosides except neomycin. Between 70% and 90% of the CNS were susceptible to cefazolin, neomycin, ciprofloxacin, ofloxacin, norfloxacin, and chloramphenicol. Less than 70% of the isolated CNS were sensitive to the penicillin analogues, ceftazidime, erythromycin, and tetracycline.Preoperative conjunctival isolates of CNS seem to be most sensitive to vancomycin, the aminoglycosides (except neomycin), and levofloxacin.

  View details for DOI 10.1016/S0161-6420(03)00735-8

  View details for Web of Science ID 000185615400015

  View details for PubMedID 14522770

• Risk factors for antibiotic-resistant conjunctival bacterial flora in patients undergoing intraocular surgery GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY de Kaspar, H. M., Shriver, E. M., Nguyen, E. V., Egbert, P. R., Singh, K., Blumenkranz, M. S., Ta, C. N. 2003; 241 (9): 730-733

  Abstract

  The purpose of this study was to determine if patients with certain risk factors are more likely to harbor conjunctival bacterial flora resistant to multiple antibiotics.In this prospective study, detailed medical history and slit-lamp examination were performed on all patients prior to intraocular surgery. Patients with local risk factors were defined as those with chronic blepharitis, conjunctivitis or discharge. Those with systemic risk factors were patients with diabetes, autoimmune, immunodeficient or skin disorders, asthma and those taking immunosuppressant medications. Conjunctival cultures were obtained prior to preoperative antibiotics and povidone-iodine. Bacteria isolated were identified and antibiotic susceptibility was determined. Bacteria resistant to five or more antibiotics were defined as multi-resistant (MR).Among the 207 patients enrolled in the study, 73 patients had local risk factors. Of these patients, 32 patients (44%) carried MR organisms, compared to 32 of the 134 patients (24%) without local risk factors (P=0.0049). Thirty-two of 71 patients (45%) with systemic risk factors harbored MR organisms, compared to 32 of 136 patients (24%) without systemic risk factors (P=0.0025). Seventeen of 93 patients (18%) who had neither local nor systemic risk factors had MR organisms on their conjunctiva. In contrast, 17 of the 30 patients (57%) with both local and systemic risk factors (57%) carried MR bacteria (P=0.0001).Patients with local and/or systemic risk factors are more likely to harbor MR organisms. This may be one mechanism for the reported increased risk of postoperative endophthalmitis in this group of patients.

  View details for DOI 10.1007/s00417-003-0742-5

  View details for Web of Science ID 000186037100008

  View details for PubMedID 12928904

• Comparison of preoperative conjunctival bacterial flora in patients undergoing glaucoma or cataract surgery Kreidl, K. O., Singh, K., de Kaspar, H. M., Ta, C. N. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2003: U369-U369

  View details for Web of Science ID 000184606802090

• Ten-fold reduction of conjunctival bacterial contamination rate using a combined 3-day application of topical ofloxacin and iodine irrigation in patients undergoing anterior segment intraocular surgery de Kaspar, H. M., Singh, G., Egbert, P. R., Haw, W. W., Nguyen, E. V., Singh, K., Blumenkranz, M. S., Ta, C. N. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2003: U344-U344

  View details for Web of Science ID 000184606801409

• Prospective randomized comparison of 3-day versus 1-hour preoperative ofloxacin prophylaxis for cataract surgery OPHTHALMOLOGY Ta, C. N., Egbert, P. R., Singh, K., Shriver, E. M., Blumenkranz, M. S., de Kaspar, H. M. 2002; 109 (11): 2036-2040

  Abstract

  To determine the efficacy of reducing conjunctival bacterial flora with topical ofloxacin when given for 3 days compared with 1 hour before surgery.Prospective, randomized, controlled trial.Ninety-two eyes from 89 patients were randomized to a control group (48 eyes) or study group (44 eyes).All patients from both groups received topical ofloxacin 0.3% 1 hour before surgery and a 5% povidone iodine scrub of the periorbital area before surgery. The patients in the study group received additional ofloxacin four times daily for 3 days before surgery.Conjunctival cultures were obtained at five separate time points and were inoculated in solid and liquid culture media. The presence of bacteria was determined, quantified, and identified.Forty-two percent of eyes in the control group had positive conjunctival culture immediately before surgery, compared with 19% of eyes in the study group (P < 0.05). Immediately after surgery, 34% and 14% of eyes had positive cultures in the control and study groups, respectively (P < 0.05). Quantitatively, fewer bacteria were isolated from eyes in the study group compared with those in the control group for culture samples that were obtained both before povidone iodine scrub and at the conclusion of surgery (P

  View details for Web of Science ID 000178778600032

  View details for PubMedID 12414411

• Combined Baerveldt glaucoma drainage implant and trabeculectomy with mitomycin C for refractory glaucoma JOURNAL OF GLAUCOMA Budenz, D. L., Scott, I. U., Nguyen, Q. H., Feuer, W., Singh, K., Nicolela, M. T., Bueche, M., Palmberg, P. F. 2002; 11 (5): 439-445

  Abstract

  To describe the surgical technique and clinical outcomes of a procedure for refractory glaucoma, concurrent Baerveldt glaucoma implant (BGI) and trabeculectomy with mitomycin C.Medical records of all patients who underwent combined Prolene-ligated BGI and trabeculectomy with mitomycin C were retrospectively reviewed. Main outcome measures were intraocular pressure (IOP), number of glaucoma medications, visual acuity, and complications. Kaplan-Meier survival analysis was used to determine success, defined as IOP < 22 mm Hg, no reoperation for glaucoma, and no loss of light perception vision.The mean +/- SD follow-up period for 38 eyes of 36 patients was 34 +/- 36 months (range, 3-121 months), during which 18 of 38 eyes (47%) required laser suture lysis of the Prolene suture. Intraocular pressure was reduced from a mean (+/- SD) preoperative value of 35.7 +/- 12.8 to 12.7 +/- 4.7 mm Hg at 1-year follow-up and 11.9 +/- 5.5 mm Hg at the last follow-up visit ( < 0.001). Number of medicines used for glaucoma was reduced from a mean +/- SD preoperative value of 2.5 +/- 0.9 to 0.5 +/- 0.6 at 1-year follow-up and 0.6 +/- 0.8 at the last follow-up visit ( < 0.001). LogMar visual acuity remained stable at mean of 1.15 +/- 0.85 preoperatively, compared with 1.14 +/- 1.05 at 1-year follow-up, but declined to 1.61 +/- 1.01 at the last follow-up visit, a loss of an average of four lines of vision ( = 0.004). Cumulative success was 91% at year 1, 86% at year 2, and 81% at year 3. Three eyes (8%) had suprachoroidal hemorrhages, one eye (3%) needed reoperation for an extruded implant, one (3%) eye had poor vision due to chronic hypotony, three eyes (8%) required additional glaucoma surgery during the postoperative period, and one eye (3%) needed revision of the implant for pressure control.Combined BGI and mitomycin C trabeculectomy provides excellent postoperative IOP control in patients with refractory glaucoma.

  View details for DOI 10.1097/01.IJG.0000029922.68321.88

  View details for Web of Science ID 000178511800013

  View details for PubMedID 12362086

• Antibiotic susceptibility pattern of coagulase-negative staphylococci in patients undergoing Intraocular surgery Ta, C. N., de Kaspar, H. M., Chang, R. T., Shriver, E. M., Egbert, P. R., Singh, K., Blumenkranz, M. S. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2002: U1275-U1275

  View details for Web of Science ID 000184606701594

• Bacterial contamination of paracentesis blades used in cataract surgery Chang, R. T., Ta, C. N., Egbert, P. R., Singh, K., Haw, W. W., Shriver, E. M., Espinosa, L., Williams, D. Y., Blumenkranz, M. S., de Kaspar, H. M. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2002: U73-U73

  View details for Web of Science ID 000184606600340

• Multiresistant Staphylococcus epidermidis on the conjunctiva prior to intraocular surgery Shriver, E. M., Ta, C. N., Egbert, P. R., Singh, K., Chang, R. T., Blumenkranz, M. S., de Kaspar, H. M. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2002: U860-U860

  View details for Web of Science ID 000184606700226

• Progression to end-stage glaucoma after laser in situ keratomileusis JOURNAL OF CATARACT AND REFRACTIVE SURGERY Shaikh, N. M., Shaikh, S., Singh, K., Manche, E. 2002; 28 (2): 356-359

  Abstract

  We describe 2 patients, one a glaucoma suspect because of family history and the other with juvenile glaucoma. Both patients developed complications after laser in situ keratomileusis that required frequent topical steroids, leading to steroid-induced glaucoma. In both cases, corneal edema from the acute rise in intraocular pressure (IOP) caused inaccurate IOP measurement by standard methods. The inability to recognize glaucoma early may have resulted in significant irreversible vision loss.

  View details for Web of Science ID 000173662600033

  View details for PubMedID 11821221

• Emerging Perspectives in Glaucoma: Optimizing 24-hour Control of Intraocular Pressure American Journal of Ophthalmology Wax MB, Camras CB, Fiscella RG, Girkin C, Singh K, Weinreb RN 2002; 133 (S): 1-10
• Setons and Serum IgG Titers to Silicone Journal of Glaucoma Shaikh S, Goldblum RS, Morse LS, Aslam R, Singh K 2002; 11 (6): 508-510
• Combined Baerveldt Glaucoma Drainage Implant and Trabeculectomy with Mitomycin C for Refractory Glaucoma Journal of Glaucoma Budenz, D., Scott IU, Nguyen QH, Feuer W, Singh K, Nicolela MT, Bueche M, Palmberg PF 2002; 11 (5): 439-445
• Combination Mitomycin C and 5-Fluorouracil Adjunctive to High Risk Trabeculectomy Tropical Ophthalmology Singh, K., Lin SA, Kim S 2002; 2 (3): 14-20
• Automated Perimetry Ophthalmology Delgado MF, Nguyen NTA, Cox TA, Singh K, Lee DA, Dueker DK, Fechtner RD, Juzych, MS, Lin SC, Netland PA, Pastor SA, Schuman JS, Samples JR 2002; 109 (12): 2362-2374
• Maximal Medical Therapy for Glaucoma. Know When to Say When Minerva Oftalmogica Singh, K., Fechtner RD 2002; 44: 1-4
• Glaucoma care in West Africa JOURNAL OF GLAUCOMA Budenz, D. L., Singh, K. 2001; 10 (4): 348-353

  Abstract

  The authors draw on the peer review literature and 8 years of personal experience to provide an overview of the prevalence and management of glaucoma in West Africa.

  View details for Web of Science ID 000170658500016

  View details for PubMedID 11558821

• Antibiotic susceptibility pattern of coagulase-negative staphylococci in patients undergoing intraocular surgery. Ta, C. N., de Kaspar, H., Egbert, P., Singh, K., Blumenkranz, M. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2001: S254-S254

  View details for Web of Science ID 000168392101365

• Immediate bacterial contamination of the aqueous humor in intraocular surgery. Braun, M., de Kaspar, H., Ta, C. N., Egbert, P., Singh, K., Blumenkranz, M. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2001: S256-S256

  View details for Web of Science ID 000168392101374

• Cyclophotocoagulation: A Report by the American Academy of Ophthalmology Ophthalmology Paster SA, Singh K, Lee DA, Juzych MS, Lin SC, Netland PA, Nguyen NT 2001; 108 (11): 2130-2138
• Non-penetrating Glaucoma Surgery Ophthalmology Netland P, Lee DA, Juzych MS, Nguyen TA, Pastor SA, Robin AL, Singh K 2001; 108 (2): 416-421
• Glaucoma Care in West Africa Journal of Glaucoma Budenz D, Singh K 2001; 10 (4): 348-353
• Maximal Glaucoma Therapy Journal of Glaucoma Fechtner RD, Singh K 2001; 10 (5): 73-75
• Trabeculectomy with intraoperative mitomycin C versus 5-fluorouracil - Prospective randomized clinical trial OPHTHALMOLOGY Singh, K., Mehta, K., Shaikh, N. M., Tsai, J. C., Moster, M. R., Budenz, D. L., Greenfield, D. S., Chen, P. P., Cohen, J. S., Baerveldt, G. S., Shaikh, S. 2000; 107 (12): 2305-2309

  Abstract

  To evaluate the relative efficacy and safety of 5-fluorouracil (5-FU) and mitomycin C (MMC) when used as adjuncts with primary trabeculectomy in eyes not at high risk for failure.Prospective multicenter, randomized clinical trial.One hundred thirteen patients with primary open-angle, pseudoexfoliative, pigmentary, or angle-closure glaucoma undergoing primary trabeculectomy were recruited.One eye of each patient was randomized to receive either 5-FU (50 mg/ml for 5 minutes) or MMC (0.4 mg/ml for 2 minutes).Intraocular pressure (IOP), visual acuity, complications, and interventions were documented at fixed intervals after surgery. The study also examined progression of visual field loss, long-term complications, and bleb appearance 3 years after surgery.Of the 108 patients with complete perioperative information, 54 eyes received 5-FU and 54 received MMC. The proportion of patients reaching different predefined target IOPs after surgery was slightly higher in the MMC group than in the 5-FU group. This difference was less than 25%, which would have been necessary to achieve statistical significance with a power of 0.8 and the sample size used. Likewise, there was no statistically significant difference between the groups with regard to mean preoperative IOP, complications, or interventions. Mean postoperative follow-up was 309 and 330 days in the 5-FU and MMC groups, respectively (P = 0.593).5-Fluorouracil and MMC were found to be equally safe and effective adjuncts to primary trabeculectomy in the short- and medium-term postoperative periods.

  View details for Web of Science ID 000165586900057

  View details for PubMedID 11097613

• Randomized Clinical Trial of Trabeculectomy with Intraoperative Mitomycin C versus 5-Fluorouracil Journal of the Organization of the Panhellenic Ophthalmological Society Singh, K. 2000; 12 (3): 244-249
• Target IOP: Glaucoma's Holey Grail Ophthalmology Singh K, Spaeth G, Zimmerman T, Minckler D 2000; 107 (4): 629-630
• Migration Patterns and Practice Choices of Newly Trained Ophthalmologists Internet Journal of Ophthalmology Gable MS, Mohr JD, Singh K 2000; 5: 01-06
• Emerging Perspective on Glaucoma American Journal of Ophthalmology Lee DA, Fechtner RD, Fiscella RG, Singh K, Stewart WC 2000; 130 (4): S1-11
• The subspecialty training, practice type, and geographical distribution of recently trained ophthalmologists: a study of male and female physicians. Journal of the American Medical Women's Association (1972) Gable, M. S., MOHR, J. D., O'Brien, T. P., Lee, P., Colenbrander, A., Singh, K. 2000; 55 (1): 20-?

  Abstract

  To characterize the distribution of male and female ophthalmologists with regard to practice type, subspecialty training, rural-urban distribution, and regional distribution.Ophthalmology Matching Program files containing the records of residents who began their second year at accredited programs between 1986 and 1990 (inclusive), were compared to membership files of the American Academy of Ophthalmology. Practice locations for each individual were classified according to region, stage, and Rural-Urban Continuum County Code, as defined by the US Department of Agriculture.This cohort comprised 2,494 individuals, 77.1% (1922) of whom were male and 22.9% (572) of whom were female. Group practice was most common (55.9% for women and 61.3% for men). More women were in salaried positions associated with health maintenance organizations (p = 0.006) and academic settings (p < 0.001) than were men. Notable differences in subspecialty choice were restricted to pediatric ophthalmology, chosen three times more frequently by women, and vitreoretinal diseases/surgery, chosen twice as often by men. Only 5.6% of women selected nonmetropolitan practice locales compared to approximately twice that percentage of men. The Middle Atlantic and New England regions attracted more women, while the South Atlantic attracted more men.

  View details for PubMedID 10680402

• Comparison of Phacotrabeculectomy with 5-Fluorouracil, Mitomycin C, and Without Antifibrotic Agents Ophthalmic Surgery and Lasers Budenz D, Pyfer M, Singh K, Gordon J, Piltz-Seymour J, Keates EU 1999; 30 (5): 367-374
• Effects of Carteolol and Timolol on Plasma Lipid Profiles in Older Women with Ocular Hypertension or Primary Open-Angle Glaucoma American Journal of Ophthalmology Stewart WC, Dubiner HB, Mundorf TK, Laibovitz RA, Sall KN, Katz LJ, Singh K. Shulman DG, Siegel LI, Hudgins AC, Nussbaum L, Apostolaros M 1999; 127 (2): 142-147
• Medical control of intraocular pressure after cataract surgery JOURNAL OF CATARACT AND REFRACTIVE SURGERY Byrd, S., Singh, K. 1998; 24 (11): 1493-1497

  Abstract

  To compare the effectiveness of 2 medications commonly used to prevent intraocular pressure (IOP) elevation in the early period after cataract surgery.Palo Alto Veterans Affairs Health Care System, Palo Alto, California, USA.This prospective study comprised 202 eyes of patients scheduled for cataract extraction who agreed to participate. Patients were randomized to receive oral acetazolamide, 500 mg 1 hour preoperatively; oral acetazolamide, 500 mg immediately postoperatively; apraclonidine hydrochloride 1%, 2 drops 1 hour preoperatively; or artificial tears (control group). Intraocular pressure was measured preoperatively and 4 to 6 and 24 hours postoperatively.Preoperative IOP was not significantly different among the 4 groups. At 4 to 6 hours postoperatively, only preoperative acetazolamide was significantly more effective than the control medication (P = .038); at 24 hours there were no significant differences among the 4 groups. Postoperative IOP elevation in excess of 35 mm Hg at 6 or 24 hours decreased significantly in the preoperative acetazolamide group (3/46 eyes) compared with the control group (14/54 eyes). There was no statistically significant difference in IOP elevation between eyes having extracapsular cataract extraction and those having phacoemulsification, independent of treatment group.The results favor preoperative acetazolamide to control postcataract IOP elevation. The method of cataract removal did not affect postoperative IOP elevation.

  View details for Web of Science ID 000076836300024

  View details for PubMedID 9818340

• Delayed corneal epitheliopathy after antimetabolite-augmented trabeculectomy JOURNAL OF GLAUCOMA Manche, E. E., Afshari, M. A., Singh, K. 1998; 7 (4): 237-239

  Abstract

  The authors describe the first case of delayed antimetabolite-related corneal epithelial toxicity after trabeculectomy and its successful treatment with limbal stem cell transplantation.A 73-year-old woman underwent trabeculectomy with intraoperative mitomycin C. After surgery she received six 5-mg injections of subconjunctival 5-fluorouracil (5-FU) adjacent to the bleb.The patient had a functioning trabeculectomy and clear cornea until 30 months after surgery, at which time she developed a nonhealing superior corneal epithelial defect. After 4 months of conservative medical management, an autologous limbal stem cell transplantation was performed. The epithelial defect resolved completely within 1 week of limbal stem cell transplantation.Delayed corneal epithelial toxicity may be a late complication of antimetabolite-augmented trabeculectomy.

  View details for Web of Science ID 000075303500004

  View details for PubMedID 9713780

• Risk of hypotony after primary trabeculectomy with antifibrotic agents in a black West African population JOURNAL OF GLAUCOMA Singh, K., Byrd, S., Egbert, P. R., Budenz, D. 1998; 7 (2): 82-85

  Abstract

  To evaluate the risk of hypotony and hypotony maculopathy following trabeculectomy with 5-fluorouracil (5-FU) and mitomycin C (MMC) in a black West African population.One hundred and one eyes of black Ghanaian patients with advanced primary open-angle glaucoma received intraoperative antifibrotic therapy with trabeculectomy as part of two randomized clinical trials. Overall, 57 patients received 5-FU (50.0 mg/ml for 5 minutes) and 44 received MMC (0.5 mg/ml for 3.5 minutes). All cases were performed by one of five surgeons at a single outpatient surgery center.Two of 101 eyes had a final intraocular pressure (IOP) of less than 5 mm Hg and were thus classified as having hypotony. No patient in either group was noted to develop hypotony-related maculopathy. Overall mean pre- and postoperative IOPs were 30.1 and 15.9 mm Hg, respectively. The patients receiving intraoperative MMC had a lower mean postoperative IOP (14.7 mm Hg) than those receiving 5-FU (first study, 17.1 mm Hg; second study, 16.7 mm Hg; p = 0.05). Mean overall follow-up was 17.7 months and did not differ significantly between the MMC and combined 5-FU groups.Hypotony following trabeculectomy supplemented with antifibrotic agents is a rare complication in this population. No eyes in either clinical trial developed hypotony maculopathy, suggesting that the prevalence of this condition is substantially lower in black West Africans than in whites.

  View details for Web of Science ID 000072804500003

  View details for PubMedID 9559492

• Inhibition of Tenon's fibroblast proliferation and collagen synthesis by clarithromycin, colchicine, verapamil and captopril Singh, K., Byrd, S. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 1997: 1234-1234

  View details for Web of Science ID A1997WN18601231

• The effect of transient hypotony on final visual acuity following combined trabeculectomy with cataract surgery Ta, C., Byrd, S., Singh, K. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 1997: 1210-1210

  View details for Web of Science ID A1997WN18601207

• Antimetabolite Application: Science or Voodoo Journal of Glaucoma Singh K 1997; 6 (5): 271-273
• Trabeculectomy with intraoperative 5-fluorouracil vs mitomycin C AMERICAN JOURNAL OF OPHTHALMOLOGY Singh, K., Egbert, P. R., Byrd, S., Budenz, D. L., Williams, A. S., Decker, J. H., Dadzie, P. 1997; 123 (1): 48-53

  Abstract

  To compare the effectiveness of intraoperative 5-fluorouracil (5-FU) and mitomycin C used adjunctively with trabeculectomy in a black West African population.Eighty-five consecutive eyes of 85 black patients undergoing primary trabeculectomy for open-angle glaucoma were prospectively randomly assigned to receive either 5-FU (50 mg/ml for 5 minutes) or mitomycin C (0.5 mg/ml for 3 1/2 minutes) intraoperatively by soaked sponge.Of the 81 eyes with at least a 3-month postoperative follow-up, 41 of 44 (93.2%) in the mitomycin C group and 27 of 37 (73.0%) in the 5-FU group had a final intraocular pressure of less than 21 mm Hg (P = .01). Twenty-eight of 44 eyes (63.6%) in the mitomycin C group and 18 of 37 (51.4%) in the 5-FU group had a final intraocular pressure of less than 15 mm Hg (P = .26). Mean postoperative intraocular pressure was 13.7 mm Hg in the mitomycin C group and 16.3 mm Hg in the 5-FU group (P = .05). There were no differences between the two groups in mean age, preoperative intraocular pressure, postoperative visual acuity, and complications. Mean follow-up was 10.0 +/- 4.41 months (range, 4 to 19 months).The adjunctive use of mitomycin C with trabeculectomy is equally safe and more efficacious compared to 5-FU in this West African population. Use of mitomycin C in this study was not associated with a statistically significantly greater proportion of patients achieving low intraocular pressure (less than 15 mm Hg) compared to 5-FU.

  View details for Web of Science ID A1997WB82200006

  View details for PubMedID 9186096

• Risk of hypotony following antimetabolite trabeculectomy in a black West African Singh, K., Egbert, P. R., Budenz, D., Dadzie, P. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 1996: 1161-1161

  View details for Web of Science ID A1996TX39701159

• Clinical Pharmacology and Use of Dorzolamide (Trusopt): A Topical Ocular Carbonic Anhydrase Inhibitor in the Treatment of Glaucoma Today's Therapeutic Trends Singh K, Zimmerman TJ 1996; 14 (2): 3
• Update on the Status of Topical Beta-Blockers in the Treatment of Glaucoma Ophthalmology Clinics of North America Singh K, Zimmerman TJ 1995; 8 (2): 295-302
• A PROSPECTIVE TRIAL OF INTRAOPERATIVE FLUOROURACIL DURING TRABECULECTOMY IN A BLACK-POPULATION AMERICAN JOURNAL OF OPHTHALMOLOGY Egbert, P. R., Williams, A. S., Singh, K., Dadzie, P., Egbert, T. B. 1993; 116 (5): 612-616

  Abstract

  In a study population of black Africans with advanced glaucoma in Ghana we conducted a prospective study of intraoperative 5-fluorouracil alone. Eyes undergoing trabeculectomy were randomly selected either to receive or not receive a single intraoperative application of 5-fluorouracil (50 mg/ml for five minutes). Fifty-five eyes had a mean follow-up of 282 days (minimum, 92 days). Twenty of 24 eyes (83%) in the 5-fluorouracil group vs 12 of 31 eyes (39%) in the control group had postoperative intraocular pressure of 20 mm Hg or less with or without medical therapy (P = .01). Eleven of 24 eyes (46%) in the 5-fluorouracil group and five of 31 eyes (16%) in the control group had intraocular pressure of 15 mm Hg or less (P = .02). Without medical therapy, 17 of 24 eyes (71%) in the 5-fluorouracil group and ten of 31 eyes (32%) in the control group had intraocular pressure of 20 mm Hg or less (P = .02). The overall complications were similar in the two groups. In this population, intraoperative 5-fluorouracil markedly improved the ability of trabeculectomy to lower intraocular pressure. We recommend that intraoperative 5-fluorouracil be considered in glaucoma surgery with poor prognosis as an alternative to postoperative subconjunctival injections when multiple injections are not feasible.

  View details for Web of Science ID A1993MF62400011

  View details for PubMedID 8238222

• COMBINED SETON IMPLANTATION AND MITOMYCIN TRABECULECTOMY Singh, K., Bueche, M., Budenz, D., Palmberg, P. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 1993: 731-731

  View details for Web of Science ID A1993KT89300137

• Glaucoma: A global problem. Seminars in Opthalmology Singh K 1993; 8 (3): 190-195
• Acute Idiopathic Blind Spot Enlargement: A Spectrum of Disease Ophthalmology Singh K, DeFrank MP, Watzke RC, Shults WT 1991; 98 (4): 497-502
• A Population-Based Evaluation of Glaucoma Screening: The Baltimore Eye Survey American Journal of Epidemiology Tielsch JM, Sommer A, Katz J. Quigley HA, Gottsch JD, Javitt J, Singh K, the Baltimore Eye Survey Research Group 1991; 134 (10): 1102-1110
• Socioeconomic Status and Visual Impairment Among Urban Americans Archives of Ophthalmology Tielsch JM, Sommer A, Katz J, Quigley H, Ezrine S, the Baltimore Eye Survey Research Group: (Sommer A, Tielsch JM, Quigley H, Gottsch J, Royall R, Katz J, Witt K, Singh K, Javitt J, Ezrine S 1991; 109 (5): 637-641
• Relationship Between Intraocular Pressure and Primary Open Angle Glaucoma Among White and Black Americans: The Baltimore Eye Survey Archives of Ophthalmology Sommer A, Tielsch JM, Katz J, Quigley HA, Gottsch JD, Javitt J, Singh K, the Baltimore Eye Survey Research Group 1991; 109 (8): 1090-1095
• Blindness and Visual Impairment in an American Urban Population: The Baltimore Eye Survey Archives of Ophthalmology Tielsch JM, Sommer A, Witt K, Katz J, Royall RM, The Baltimore Eye Survey Research Group: (Sommer A, Tielsch JM, Quigley H, Gottsch J, Royall R, Katz J, Witt K, Singh K 1990; 108 (2): 286-290
• Intraocular Lens Power Calculations: A Practical Evaluation in Normal Subjects at the Wilmer Institute Archives of Ophthalmology Singh K, Sommer A, Jensen AD, Payne JW 1987; 105 (8): 1046-1050