Bio

Bio


Dr. Chang runs a busy glaucoma and cataract surgical practice with special expertise in minimally invasive glaucoma surgery (MIGS such as iStent, ECP, trabectome, soon Cypass, Aquesys) and complex cataract removal using the latest technologies including intraop aberrometry and toric lenses. He is an expert on optical coherence tomography (OCT) having helped the development of Zeiss Cirrus. He emphasizes precision medicine using OCT and visual fields. Besides state of the art clinical care, cutting edge research, and world class education (> 95 lectures including international teaching and volunteer work), he is involved in the development of novel mobile health devices and digital health startups as well as scientific advisor to multiple pharmaceutical and medical device companies. Current research interests include: differentiating high myopia from glaucoma, improving glaucoma medication compliance, eye care screening with mobile devices, computer vision machine learning, and validating and commercializing new medical devices.

Dr. Chang co-invented the EyeGo Smartphone imaging adapter, which was licensed to Digisight Technologies (now called the PAXOS scope https://www.digisight.net/digisight/paxos-scope.php). He brings translational medtech to the market to improve patient care. He is also the co-creator of an immersive, cross-cultural Stanford-China entrepreneurship graduate seminar (www.dhealthchina.com) and leads several hybrid biodesign hackathon seminars including Hong Kong (www.dreamcatchers.hku.hk/?p=1268), Brazil (www.hipuc.com), Beijing, and Stanford. He is a Fellow of the Stanford Center of Innovation for Global Health, a Biodesign Faculty Fellow, and Lean Launchpad educator. He also won first place in the 2015 Philips Healthsuite Hackathon and the 2016 Robert Howard Design Award to improve his team's latest consumer medtech wearable for air pollution.

Clinical Focus


  • Ophthalmology
  • Glaucoma and cataract surgery
  • Minimally Invasive Surgical Procedures
  • Medical Education
  • Mobile Health
  • Optical Coherence Tomography
  • Myopia
  • Vision Screening
  • trabectome
  • istent
  • ECP

Academic Appointments


Administrative Appointments


  • Medical Director, Stanford Employer Based Optometry (2016 - Present)
  • Glaucoma Fellowship Co-Director, Stanford Ophthalmology (2009 - Present)

Honors & Awards


  • Heed Fellow, Heed Foundation (2007)
  • America Glaucoma Society MAPS grant, AGS (2011)
  • Bio-X Undergraduate Summer Research Program Grant, Stanford (2013)
  • Winner Best Pivot, Stanford Startxmed Innovation Challenge (2013)
  • Stanford Society of Physician Scholars (SSPS) Grant, SSPS (2014)
  • Stanford Spectrum Medtech Innovation Grant, Spectrum (2014)
  • Circular 2D Polarized LCD TV on Improvement of Eye Fatigue and Eye Movement Control, TCL Research America Grant (2014-2015)
  • First Place, Philips Healthsuite Hackathon (2015)
  • Robert Howard Next Step Award, Lunar (2016)
  • Stanford Center Peking University Graduate Seminar Program, SCPKU (June 2015)
  • Stanford Center Peking University Faculty Fellowship Program Award, SCPKU (May 2014)

Boards, Advisory Committees, Professional Organizations


  • Fellow, AAO American Academy of Ophthalmology (2009 - Present)
  • Member, AGS American Glaucoma Society (2009 - Present)
  • Fellow, CIGH Center for Innovation in Global Health (2015 - Present)
  • Member and Co-Chair mHealth, PHS Population Health Sciences (2015 - Present)
  • Vice President, APTOS Asia Pacific Tele-Ophthalmology Society (2016 - Present)

Professional Education


  • Residency:Washington University in St Louis (2007) MO
  • Fellowship:Bascom Palmer Eye Institute (2009) FL
  • Internship:Northshore University Health System (2004) IL
  • Medical Education:University of Missouri (2002) MO
  • Board Certification: Ophthalmology, American Board of Ophthalmology (2008)

Community and International Work


  • Stanford Center at Peking University (SCPKU) Ignite Health, Beijing

    Topic

    digital health biodesign seminar

    Partnering Organization(s)

    Peking University PKU

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    Yes

  • Smartphone Imaging

    Topic

    anterior and posterior segment imaging capture with the iPhone

    Partnering Organization(s)

    Digisight Technologies

    Populations Served

    China and India

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    Yes

  • Lifeline Express Volunteer Educator, Lanzhou, Mianyang, Nanjing, Urumqi, Zhengzhou, Jilin, Huanggang, Shantou, Beijing, Guangzhou, etc.

    Topic

    cataract and glaucoma lecturer

    Partnering Organization(s)

    China Lifeline Express Foundation

    Populations Served

    rural China

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    No

Patents


  • Robert Chang. "United States Patent 62/138,271 Modular Smartphone Adapters for Mobile Ophthalmoscopy", Leland Stanford Junior University, Mar 25, 2015
  • Robert Chang. "United States Patent 14/893,951 Modular Lens Adapters for Mobile Anterior and Posterior Segment Ophthalmoscopy,", Leland Stanford Junior University, May 30, 2014

Research & Scholarship

Current Research and Scholarly Interests


I am a clinician-scientist focusing on patient care, physician innovation and biodesign educator, and digital health technology.

Selected Interests:
1) Young Chinese Myopes with Minimally Progressive Field Defects
2) Visual Field and Optical Coherence Tomography Specificity for Progression in Glaucoma
3) Patient Satisfaction in Ophthalmology
4) Automated Visual Field Screening for Glaucoma Using Mobile Devices
5) Smartphone-Based Tele-Ophthalmology Screening For Eye Disease
6) Smartphone-Based Contrast Sensitivity Testing and the Mobile Eye Exam
7) Computer Vision Machine Learning for Ophthalmology
8) Compliance with Medication Monitoring and Realtime Intervention

Clinical Trials


  • Safety and Efficacy of Bimatoprost Sustained-Release (SR) in Patients With Open-Angle Glaucoma or Ocular Hypertension Recruiting

    This study will evaluate the efficacy and safety of bimatoprost sustained-release (SR) in patients with open-angle glaucoma or ocular hypertension. The study includes a 12-month treatment period with an 8-month extended follow-up.

    View full details

  • Comparing Safety and Efficacy of BOL-303259-X With Timolol Maleate in Subjects With Open-Angle Glaucoma or Ocular Hypertension Not Recruiting

    In participants with a diagnosis of open angle glaucoma (OAG) or ocular hypertension (OHT), the primary objective is to demonstrate that the mean IOP reduction after 3 months of treatment with BOL-303259-X once daily (QD) is non-inferior to timolol maleate 0.5% twice daily (BID). The secondary objective is to demonstrate the superiority of BOL-303259-X QD to timolol maleate 0.5% BID. This assessment will be performed if the non-inferiority of BOL-303259-X QD to timolol maleate 0.5% BID is determined. An open label safety phase will be conducted at the end of Visit 6 (3 months) where all participants will receive BOL-303259-X QD for an additional 9 months.

    Stanford is currently not accepting patients for this trial. For more information, please contact Zayna Shaheen, 650 497-9205 .

    View full details

Teaching

2015-16 Courses


Stanford Advisees


Publications

All Publications


  • Glaucoma Suspect: Diagnosis and Management. Asia-Pacific journal of ophthalmology (Philadelphia, Pa.) Chang, R. T., Singh, K. ; 5 (1): 32-7

    Abstract

    Glaucoma suspect is a diagnosis reserved for individuals who do not definitively have glaucoma at the present time but have characteristics suggesting that they are at high risk of developing the disease in the future based on a variety of factors. This review provides a practical approach to individuals classified as glaucoma suspects caused by one or more of the following risk factors or indicators of disease: ocular hypertension, optic nerve features suggestive of glaucoma, visual field abnormalities, and other characteristics placing them at greater risk than the average population. In addition to diagnostic considerations, this overview provides information on therapeutic approaches to the glaucoma suspect.

    View details for DOI 10.1097/APO.0000000000000173

    View details for PubMedID 26886117

  • Update on the Medical Treatment of Primary Open-Angle Glaucoma. Asia-Pacific journal of ophthalmology (Philadelphia, Pa.) Cheema, A., Chang, R. T., Shrivastava, A., Singh, K. ; 5 (1): 51-8

    Abstract

    Glaucoma comprises a group of progressive, neurodegenerative disorders characterized by retinal ganglion cell death and nerve fiber layer atrophy. Several randomized controlled trials have consistently demonstrated the efficacy of intraocular pressure lowering to slow or halt the measurable progression of the disease. Medical therapy, in places where it is easily accessible, is often the primary method to lower intraocular pressure. We review the medical options currently available and possible future options currently in development. The 5 contemporary classes of topical agents in use include prostaglandin analogs, beta blockers, carbonic anhydrase inhibitors, alpha agonists, and cholinergics. In addition, several fixed combination agents are commercially available. Agents from each of these classes have unique mechanisms of action, adverse effects, and other characteristics that impact how they are used in clinical practice. Despite the plethora of medical options available, there are limitations to topical ophthalmic therapy such as the high rate of noncompliance and local and systemic adverse effects. Alternate and sustained drug delivery models, such as injectable agents and punctal plug delivery systems, may in the future alleviate some such concerns and lead to increased efficacy of treatment while minimizing adverse effects.

    View details for DOI 10.1097/APO.0000000000000181

    View details for PubMedID 26886120

  • 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 PubMedID 26893029

  • 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

    Abstract

    To determine which metrics from the Press Ganey patient satisfaction survey best correlate with "likelihood to recommend" among patients in an academic tertiary medical center practice setting.Cross-sectional study.Over a 3-month period, patients presenting to an academic practice who agreed to participate were enrolled in the study if they met the following entry criteria: (1) age ≥18 years, (2) ability to read and speak English, and (3) followed in this practice between 4 months and 4 years. A total of 196 patients were recruited.A 26-item abridged version of the Press Ganey survey typically distributed to patients via mail or e-mail after visiting the Stanford University Hospital was administered privately to each eligible patient of 2 different attending clinics at the conclusion of his or her visit. The 26 survey items were not modified for the purposes of the study and were administered such that participants could not be individually identified. The arithmetic mean score for the item "Likelihood of your recommending our practice to others" was calculated by assigning a value (0-100) to the Likert value associated with survey responses and correlated with the 25 other items using the differences in the mean scores.Response to survey items graded on a 1 to 5 standard Likert scale.The weighted mean patient survey score for the "likelihood to recommend" item for the junior faculty member was 95.9% and for the senior faculty member was 94.5%, respectively. For the remaining 25 items, "Amount of time the care provider spent with you" (Diff[1-2]=1.03; P < 0.0001) and "Ease of scheduling your appointment" (Diff[1-2]=0.99; P < 0.0001) best correlated with likelihood to recommend. In contrast, "Friendliness/courtesy of the care provider" (Diff[1-2]=0.29; P = 0.0045) correlated least with likelihood to recommend. Stratification based on provider did not affect the study results.The perception of time spent with the practitioner and ease of appointment scheduling are the 2 variables that best correlate with patients recommending their ophthalmologists to other prospective patients.

    View details for DOI 10.1016/j.ophtha.2015.09.044

    View details for PubMedID 26545321

  • Smartphone-Based Dilated Fundus Photography and Near Visual Acuity Testing as Inexpensive Screening Tools to Detect Referral Warranted Diabetic Eye Disease. Retina (Philadelphia, Pa.) Toy, B. C., Myung, D. J., He, L., Pan, C. K., Chang, R. T., Polkinhorne, A., Merrell, D., Foster, D., Blumenkranz, M. S. 2016

    Abstract

    To compare clinical assessment of diabetic eye disease by standard dilated examination with data gathered using a smartphone-based store-and-forward teleophthalmology platform.100 eyes of 50 adult patients with diabetes from a health care safety-net ophthalmology clinic. All patients underwent comprehensive ophthalmic examination. Concurrently, a smartphone was used to estimate near visual acuity and capture anterior and dilated posterior segment photographs, which underwent masked, standardized review. Quantitative comparison of clinic and smartphone-based data using descriptive, kappa, Bland-Altman, and receiver operating characteristic analyses was performed.Smartphone visual acuity was successfully measured in all eyes. Anterior and posterior segment photography was of sufficient quality to grade in 96 and 98 eyes, respectively. There was good correlation between clinical Snellen and smartphone visual acuity measurements (rho = 0.91). Smartphone-acquired fundus photographs demonstrated 91% sensitivity and 99% specificity to detect moderate nonproliferative and worse diabetic retinopathy, with good agreement between clinic and photograph grades (kappa = 0.91 ± 0.1, P < 0.001; AUROC = 0.97, 95% confidence interval, 0.93-1).The authors report a smartphone-based telemedicine system that demonstrated sensitivity and specificity to detect referral-warranted diabetic eye disease as a proof-of-concept. Additional studies are warranted to evaluate this approach to expanding screening for diabetic retinopathy.

    View details for DOI 10.1097/IAE.0000000000000955

    View details for PubMedID 26807627

  • A novel smartphone ophthalmic imaging adapter: User feasibility studies in Hyderabad, India. Indian journal of ophthalmology Ludwig, C. A., Murthy, S. I., Pappuru, R. R., Jais, A., Myung, D. J., Chang, R. T. 2016; 64 (3): 191-200

    Abstract

    To evaluate the ability of ancillary health staff to use a novel smartphone imaging adapter system (EyeGo, now known as Paxos Scope) to capture images of sufficient quality to exclude emergent eye findings. Secondary aims were to assess user and patient experiences during image acquisition, interuser reproducibility, and subjective image quality.The system captures images using a macro lens and an indirect ophthalmoscopy lens coupled with an iPhone 5S. We conducted a prospective cohort study of 229 consecutive patients presenting to L. V. Prasad Eye Institute, Hyderabad, India. Primary outcome measure was mean photographic quality (FOTO-ED study 1-5 scale, 5 best). 210 patients and eight users completed surveys assessing comfort and ease of use. For 46 patients, two users imaged the same patient's eyes sequentially. For 182 patients, photos taken with the EyeGo system were compared to images taken by existing clinic cameras: a BX 900 slit-lamp with a Canon EOS 40D Digital Camera and an FF 450 plus Fundus Camera with VISUPAC™ Digital Imaging System. Images were graded post hoc by a reviewer blinded to diagnosis.Nine users acquired 719 useable images and 253 videos of 229 patients. Mean image quality was ≥ 4.0/5.0 (able to exclude subtle findings) for all users. 8/8 users and 189/210 patients surveyed were comfortable with the EyeGo device on a 5-point Likert scale. For 21 patients imaged with the anterior adapter by two users, a weighted κ of 0.597 (95% confidence interval: 0.389-0.806) indicated moderate reproducibility. High level of agreement between EyeGo and existing clinic cameras (92.6% anterior, 84.4% posterior) was found.The novel, ophthalmic imaging system is easily learned by ancillary eye care providers, well tolerated by patients, and captures high-quality images of eye findings.

    View details for DOI 10.4103/0301-4738.181742

    View details for PubMedID 27146928

  • Visual field defect classification in the Zhongshan Ophthalmic Center-Brien Holden Vision Institute High Myopia Registry Study. The British journal of ophthalmology Ding, X., Chang, R. T., Guo, X., Liu, X., Johnson, C. A., Holden, B. A., He, M. 2016

    Abstract

    To describe a new combined myopia and glaucoma visual field classification system in order to report the visual field defects in a population of mostly young Chinese high myopes aged 7-70 years.A total of 1434 visual fields (including confirmatory repeats of abnormal defects) from 487 high myopes (sphere ≤-6.0 D) were analysed from the prospective Zhongshan Ophthalmic Center-Brien Holden Vision Institute (ZOC-BHVI) High Myopia Registry Study. The predefined classification definitions covering high myopia and glaucoma categories were: normal, enlarged blind spot, abnormal suspect and abnormal with nine subtypes. Two independent graders reviewed the first 150 of 1434 fields for initial grading calibration and the remaining 1284 fields were used to assess intergrader agreement. For the percentage distribution of visual fields, the repeats and unreliable fields were excluded, leaving 894 fields.The intergrader agreement of this combined classification system was a κ value of 0.61 (95% CI 0.59 to 0.63). Among the 894 unique fields, the most common visual field was normal at 33.7% followed by enlarged blind spot at 25.6%. The per cent of 'arcuate-like' field defects (combining nasal step, early arcuate and advanced arcuate) was 16.1% with advanced arcuate at 3.4%.A proposed combined visual field classification for high myopia and glaucoma demonstrates acceptable intergrader agreement. A total of 16.1% of defects in young high myopes were found to mimic classic glaucomatous defects. These subjects are being followed prospectively to assess which ones will progress to differentiate myopic from glaucomatous field defects.

    View details for DOI 10.1136/bjophthalmol-2015-307942

    View details for PubMedID 27033693

  • 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

  • Reversible Conjunctival Pigmentation Associated With Prostaglandin Use. Journal of glaucoma Choi, D. Y., Chang, R. T., Yegnashankaran, K., Friedman, N. J. 2015

    Abstract

    A 54-year-old Indian male with a diagnosis of ocular hypertension was started on a prostaglandin analog (PGA) in both eyes to lower intraocular pressure. Six years later, he developed progressively increasing bilateral limbal conjunctival hyperpigmentation. Travoprost was discontinued and replaced with brinzolamide and over the next year, the patient's conjunctival pigmentation improved significantly in both the eyes. This case report documents with slit-lamp photography the first case of conjunctival pigmentation associated with PGA use that has been shown to have reversal with discontinuation of the PGA. Because of the widespread use of PGAs, and the evolving nature of the conjunctival pigmentation, clinicians should be aware of this reversible condition when considering biopsy or removal of conjunctival melanocytic lesions.

    View details for DOI 10.1097/IJG.0000000000000255

    View details for PubMedID 25967530

  • 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. 2015

    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 PubMedID 26035421

  • Effectiveness of low vision services in improving patient quality of life at Aravind Eye Hospital. Indian journal of ophthalmology Do, A. T., Ilango, K., Ramasamy, D., Kalidasan, S., Balakrishnan, V., Chang, R. T. 2014; 62 (12): 1125-1131

    Abstract

    In India, where the heavy burden of visual impairment exists, low vision services are scarce and under-utilized.Our study was designed to survey the effectiveness of low vision exams and visual aids in improving patient quality of life in southern rural India.The low vision quality of life (LVQOL) questionnaire measures vision-related quality of life through 25 questions on a Likert scale of 0-5 that pertain to (1) mobility, distance vision, and lighting; (2) psychological adjustment; (3) reading and fine work; and (4) activities of daily living. This tool was translated into Tamil and verbally administered to 55 new low vision referral patients before their first visit at the low vision clinic at Aravind Eye Hospital. Low vision aids (LVAs) were prescribed at the discretion of the low vision specialist. 1-month later, the same questionnaire was administered over the phone.About 44 of 55 low vision patients completed baseline and follow-up LVQOL surveys, and 30 normal vision controls matched for age, gender, and education were also surveyed (average 117.34 points). After the low vision clinic visit, the low vision group demonstrated a 4.55-point improvement in quality of life (from 77.77 to 82.33 points, P = 0.001). Adjusting for age, gender, and education, the low vision patients who also received LVAs (n = 24) experienced an even larger increase than those who did not (n = 20) (8.89 points, P < 0.001).Low vision services and visual aids can improve the quality of life in South Indian rural population regardless of age, gender, and education level. Thus, all low vision patients who meet the criteria should be referred for evaluation.

    View details for DOI 10.4103/0301-4738.149130

    View details for PubMedID 25579355

  • Optic nerve pit-associated choroidal cleft. JAMA ophthalmology Silva, R. A., Chang, R. T., Moshfeghi, D. M., Leng, T. 2014; 132 (9): 1142-?

    View details for DOI 10.1001/jamaophthalmol.2014.174

    View details for PubMedID 25058335

  • Diagnostic performance of optical coherence tomography ganglion cell-inner plexiform layer thickness measurements in early glaucoma. Ophthalmology Mwanza, J., Budenz, D. L., Godfrey, D. G., Neelakantan, A., Sayyad, F. E., Chang, R. T., Lee, R. K. 2014; 121 (4): 849-854

    Abstract

    To evaluate the glaucoma diagnostic performance of ganglion cell inner-plexiform layer (GCIPL) parameters used individually and in combination with retinal nerve fiber layer (RNFL) or optic nerve head (ONH) parameters measured with Cirrus HD-OCT (Carl Zeiss Meditec, Inc, Dublin, CA).Prospective cross-sectional study.Fifty patients with early perimetric glaucoma and 49 age-matched healthy subjects.Three peripapillary RNFL and 3 macular GCIPL scans were obtained in 1 eye of each participant. A patient was considered glaucomatous if at least 2 of the 3 RNFL or GCIPL scans had the average or at least 1 sector measurement flagged at 1% to 5% or less than 1%. The diagnostic performance was determined for each GCIPL, RNFL, and ONH parameter as well as for binary or-logic and and-logic combinations of GCIPL with RNFL or ONH parameters.Sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR).Among GCIPL parameters, the minimum had the best diagnostic performance (sensitivity, 82.0%; specificity, 87.8%; PLR, 6.69; and NLR, 0.21). Inferior quadrant was the best RNFL parameter (sensitivity, 74%; specificity, 95.9%; PLR, 18.13; and NLR, 0.27), as was rim area (sensitivity, 68%; specificity, 98%; PLR, 33.3; and NLR, 0.33) among ONH parameters. The or-logic combination of minimum GCIPL and average RNFL provided the overall best diagnostic performance (sensitivity, 94%; specificity, 85.7%; PRL, 6.58; and NLR, 0.07) as compared with the best RNFL, best ONH, and best and-logic combination (minimum GCIPL and inferior quadrant RNFL; sensitivity, 64%; specificity, 100%; PLR, infinity; and NPR, 0.36).The binary or-logic combination of minimum GCIPL and average RNFL or rim area provides better diagnostic performances than those of and-logic combinations or best single GCIPL, RNFL, or ONH parameters. This finding may be clinically valuable for the diagnosis of early glaucoma.

    View details for DOI 10.1016/j.ophtha.2013.10.044

    View details for PubMedID 24393348

  • 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

  • Technological Advances in 24-hr IOP Monitoring Glaucoma Today Chang, R. T. 2014; 12 (4)
  • Smartphone Photography Expected to Accelerate the Age of Telemedicine Ophthalmology Times Chang, R. T. 2014; 39 (11)
  • Advancements in Smartphone Photography of the Eye Cataract and Refractive Surgery Today Europe Chang, R. T., Myung, D. 2014; 9 (8)
  • Parallel rarebits: A novel, large-scale visual field screening method. Clinical & experimental optometry : journal of the Australian Optometrical Association Lin, S. R., Fijalkowski, N., Lin, B. R., Li, F., Singh, K., Chang, R. T. 2014; 97 (6): 528-33

    Abstract

    Rarebit perimetry (RBP) is a computer-based perimetric testing program with sensitivity and specificity for detection of visual field defects comparable to traditional automated perimetry. To make large-scale screening more efficient, we developed a parallel rarebit perimetric method to screen groups of subjects simultaneously. We then used this method to report the mean hit rate (MHR) among subjects aged 13 to 19 years.Rarebit perimetry was installed on computers in an existing school computer laboratory. All subjects provided medical and demographic information and underwent a basic visual examination. Testing instructions were provided to groups of up to 35 subjects and rarebit perimetry was subsequently administered. Two or three test supervisors answered questions and ensured that subjects were well aligned with their test screens. Mean hit rate, reaction times, error rates and testing time were calculated, and time estimates for rarebit, frequency doubling perimetry and Humphrey 24-2 Swedish Interactive Thresholding Algorithm (SITA) fast test were compared.A total of 364 rarebit perimetric tests were conducted on 182 subjects. Of these, 154 subjects met our inclusion criteria for the reference range (three testing errors or less and visual acuity 6/9 or better). The average mean hit rate was 94.3 ± 4.63 per cent. Screening of 500 subjects using this parallel rarebit perimetric method would require approximately nine hours, which is far less than an estimated 77 hours required for frequency doubling perimetry C-20 screening tests or an estimated 127 hours required for Humphrey 24-2 SITA fast tests.Using our methods, rarebit perimetry can be administered in parallel to groups of subjects. The mean hit rate was comparable to that reported in previously published studies. This parallel technique may improve the efficiency of large-scale visual field screenings.

    View details for DOI 10.1111/cxo.12221

    View details for PubMedID 25331077

  • An emerging treatment option for glaucoma: Rho kinase inhibitors. Clinical ophthalmology (Auckland, N.Z.) Wang, S. K., Chang, R. T. 2014; 8: 883-890

    Abstract

    Rho kinase (ROCK) inhibitors are a novel potential class of glaucoma therapeutics with multiple compounds currently in Phase II and III US Food and Drug Administration trials in the United States. These selective agents work by relaxing the trabecular meshwork through inhibition of the actin cytoskeleton contractile tone of smooth muscle. This results in increased aqueous outflow directly through the trabecular meshwork, achieving lower intraocular pressures in a range similar to prostaglandins. There are also animal studies indicating that ROCK inhibitors may improve blood flow to the optic nerve, increase ganglion cell survival, and reduce bleb scarring in glaucoma surgery. Given the multiple beneficial effects for glaucoma patients, ROCK inhibitors are certainly a highly anticipated emerging treatment option for glaucoma.

    View details for DOI 10.2147/OPTH.S41000

    View details for PubMedID 24872673

  • Simple, Low-Cost Smartphone Adapter for Rapid, High Quality Ocular Anterior Segment Imaging: A Photo Diary Journal of Mobile Technology and Medicine Myung, D., Jais, A., He, L., Chang, R. T. 2014; 3 (1)
  • Combining Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry for Glaucoma Detection. Journal of glaucoma Mwanza, J. C., Warren, J. L., Hochberg, J. T., Budenz, D. L., Chang, R. T., Ramulu, P. Y. 2014

    Abstract

    To determine the ability of frequency doubling technology (FDT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) to detect glaucoma when used individually and in combination.One hundred ten normal and 114 glaucomatous subjects were tested with FDT C-20-5 screening protocol and the GDx-VCC. The discriminating ability was tested for each device individually and for both devices combined using GDx-NFI, GDx-TSNIT, number of missed points of FDT, and normal or abnormal FDT. Measures of discrimination included sensitivity, specificity, area under the curve (AUC), Akaike's information criterion (AIC), and prediction confidence interval lengths.For detecting glaucoma regardless of severity, the multivariable model resulting from the combination of GDx-TSNIT, number of abnormal points on FDT (NAP-FDT), and the interaction GDx-TSNIT×NAP-FDT (AIC: 88.28, AUC: 0.959, sensitivity: 94.6%, specificity: 89.5%) outperformed the best single-variable model provided by GDx-NFI (AIC: 120.88, AUC: 0.914, sensitivity: 87.8%, specificity: 84.2%). The multivariable model combining GDx-TSNIT, NAP-FDT, and interaction GDx-TSNIT×NAP-FDT consistently provided better discriminating abilities for detecting early, moderate, and severe glaucoma than the best single-variable models.The multivariable model including GDx-TSNIT, NAP-FDT, and the interaction GDx-TSNIT×NAP-FDT provides the best glaucoma prediction compared with all other multivariable and univariable models. Combining the FDT C-20-5 screening protocol and GDx-VCC improves glaucoma detection compared with using GDx or FDT alone.

    View details for DOI 10.1097/IJG.0000000000000065

    View details for PubMedID 24777046

  • 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

  • Fundus Photography Still a Valuable Tool in Glaucoma Care Ophthalmology Times Chang, R. T. 2013; 38 (8)
  • A New Look at Corneal Biomechanics Ophthalmology Times Chang, R. T. 2013; 38 (16)
  • 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

  • Glaucoma Diagnostic Accuracy of Ganglion Cell-Inner Plexiform Layer Thickness: Comparison with Nerve Fiber Layer and Optic Nerve Head OPHTHALMOLOGY Mwanza, J., Durbin, M. K., Budenz, D. L., Sayyad, F. E., Chang, R. T., Neelakantan, A., Godfrey, D. G., Carter, R., Crandall, A. S. 2012; 119 (6): 1151-1158

    Abstract

    To determine the diagnostic performance of macular ganglion cell-inner plexiform layer (GCIPL) thickness measured with the Cirrus high-definition optical coherence tomography (HD-OCT) ganglion cell analysis (GCA) algorithm (Carl Zeiss Meditec, Dublin, CA) to discriminate normal eyes and eyes with early glaucoma and to compare it with that of peripapillary retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) measurements.Evaluation of diagnostic test or technology.Fifty-eight patients with early glaucoma and 99 age-matched normal subjects.Macular GCIPL and peripapillary RNFL thicknesses and ONH parameters were measured in each participant, and their diagnostic abilities were compared.Area under the curve (AUC) of the receiver operating characteristic.The GCIPL parameters with the best AUCs were the minimum (0.959), inferotemporal (0.956), average (0.935), superotemporal (0.919), and inferior sector (0.918). There were no significant differences between these AUCs and those of inferior quadrant (0.939), average (0.936), and superior quadrant RNFL (0.933); vertical cup-to-disc diameter ratio (0.962); cup-to-disc area ratio (0.933); and rim area (0.910), all P>0.05.The ability of macular GCIPL parameters to discriminate normal eyes and eyes with early glaucoma is high and comparable to that of the best peripapillary RNFL and ONH parameters.Proprietary or commercial disclosure may be found after the references.

    View details for DOI 10.1016/j.ophtha.2011.12.014

    View details for Web of Science ID 000304717100010

    View details for PubMedID 22365056

  • Risk Factors for Visual Field Progression View on Glaucoma Chang RT, Singh K 2012; 7 (1): 18-22
  • Cyclodialysis Cleft Glaucoma Today Chang RT 2012; May/June: 40
  • High Myopia Poses Challenges Ophthalmology Times Chang RT 2012; 37 (12)
  • Macular Ganglion Cell-Inner Plexiform Layer: Automated Detection and Thickness Reproducibility with Spectral Domain-Optical Coherence Tomography in Glaucoma INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Mwanza, J., Oakley, J. D., Budenz, D. L., Chang, R. T., Knight, O. J., Feuer, W. J. 2011; 52 (11): 8323-8329

    Abstract

    To demonstrate the capability of SD-OCT to measure macular retinal ganglion cell-inner plexiform layer (GCIPL) thickness and to assess its reproducibility in glaucomatous eyes.Fifty-one glaucomatous eyes (26 mild, 11 moderate, 14 severe) of 51 patients underwent macular scanning using the Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA) macula 200×200 acquisition protocol. Five scans were obtained on 5 days within 2 months. The ganglion cell analysis (GCA) algorithm was used to detect the macular GCIPL and to measure the thickness of the overall average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL. The reproducibility of the measurements was evaluated with intraclass correlation coefficients (ICCs), coefficients of variation (COVs), and test-retest standard deviations (TRTSDs).Segmentation and measurement of GCIPL thickness were successful in 50 of 51 subjects. All ICCs ranged between 0.94 and 0.98, but ICCs for average and superior GCIPL parameters (0.97-0.98) were slightly higher than for inferior GCIPL parameters (0.94-0.97). All COVs were <5%, with 1.8% for average GCIPL and COVs for superior GCIPL parameters (2.2%-3.0%) slightly lower than those for inferior GCIPL parameters (2.5%-3.6%). The TRTSD was lowest for average GCIPL (1.16 ?m) and varied from 1.43 to 2.15 ?m for sectoral GCIPL CONCLUSIONS: The Cirrus HD-OCT GCA algorithm can successfully segment macular GCIPL and measure GCIPL thickness with excellent intervisit reproducibility. Longitudinal monitoring of GCIPL thickness may be possible with Cirrus HD-OCT for assessing glaucoma progression.

    View details for DOI 10.1167/iovs.11-7962

    View details for Web of Science ID 000296907700012

    View details for PubMedID 21917932

  • Myopia and glaucoma. International ophthalmology clinics Chang, R. T. 2011; 51 (3): 53-63

    View details for DOI 10.1097/IIO.0b013e31821e5342

    View details for PubMedID 21633238

  • Reproducibility of Peripapillary Retinal Nerve Fiber Layer Thickness and Optic Nerve Head Parameters Measured with Cirrus HD-OCT in Glaucomatous Eyes INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Mwanza, J., Chang, R. T., Budenz, D. L., Durbin, M. K., Gendy, M. G., Shi, W., Feuer, W. J. 2010; 51 (11): 5724-5730

    Abstract

    To assess the reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters measured with Cirrus HD-OCT in glaucomatous eyes.Fifty-five glaucomatous eyes were included in the study. The optic disc cube 200 × 200 protocol was used to obtain three scans during the same visit to evaluate the intravisit reproducibility. One scan on 4 additional days within a 2-month period of the first session was obtained to assess intervisit reproducibility. Intraclass correlation coefficient (ICC), coefficient of variation (CV), and test-retest SD (TRT SD) were calculated for each RNFL and ONH parameter. The formula 1.645 × ?2 × intervisit TRT SD provides an upper tolerance limit to variability beyond which nonphysiologic change should be considered.All ICCs were excellent, ranging from 83.9% to 99.2% for intravisit measurements and from 80.8% to 99.1% for intervisit measurements. Cup/disc area ratio had the lowest CV (1.1%) in either type of measurement, followed by average RNFL thickness (1.9% and 2.7%). Nasal clock hours and quadrants showed the poorest reproducibility as did the clock hour directly temporally. The intervisit tolerance limit for average RNFL thickness was 3.89 ?m.Intravisit and intervisit measurements of peripapillary RNFL thickness and ONH parameters with Cirrus HD-OCT showed excellent reproducibility, indicating that this instrument may be useful in monitoring glaucoma progression. When comparing two measurements from the same eye on two different visits, a reproducible decrease in average RNFL thickness of approximately 4 ?m or more may be considered a statistically significant change from baseline.

    View details for DOI 10.1167/iovs.10-5222

    View details for Web of Science ID 000283558400041

    View details for PubMedID 20574014

  • The Utility of the Monocular Trial Data from the Ocular Hypertension Treatment Study OPHTHALMOLOGY Bhorade, A. M., Wilson, B. S., Gordon, M. O., Palmberg, P., Weinreb, R. N., Miller, E., Chang, R. T., Kass, M. A. 2010; 117 (11): 2047-2054

    Abstract

    To determine whether adjusting the intraocular pressure (IOP) change of the trial eye for the IOP change of the fellow eye (i.e., monocular trial) is a better assessment of medication response than testing each eye independently.Analysis of data from a prospective, randomized, clinical trial.Two hundred six participants with ocular hypertension randomized to the observation group and later started on a topical prostaglandin analog (PGA).Participants were started on a topical PGA in 1 eye and returned in approximately 1 month to determine medication response. The IOP response of the trial eye was determined by the IOP change between baseline and 1 month in the trial eye alone (unadjusted method) and by adjusting for the IOP change in the fellow eye between the same visits (adjusted method). Our "gold standard" for medication response was the IOP change in the trial eye between up to 3 pre- and 3 posttreatment visits on the same medication. Pearson correlation was used to compare the gold standard with the unadjusted and adjusted methods. In addition, symmetry of IOP response between trial and fellow eyes to the same medication was determined by correlating the trial eye IOP change between up to 3 pre- and 3 posttreatment visits to the fellow eye IOP change between the same visits.Correlations of IOP change of the trial eye using the gold standard to the IOP change of the trial eye using the unadjusted and adjusted methods.The correlations of IOP change using the gold standard to the IOP change using the unadjusted and adjusted methods were r = 0.40 and r = 0.41, respectively. The correlation of IOP change of both eyes between the same pre- and posttreatment visits was r = 0.81.The monocular trial (i.e., adjusted method) appears equivalent to testing each eye independently (i.e., unadjusted method); however, neither method is adequate to determine medication response to topical PGAs. Both eyes have a similar IOP response to the same PGA. Further studies to understand IOP fluctuation are necessary to improve current methods of assessing medication response.Proprietary or commercial disclosure may be found after the references.

    View details for DOI 10.1016/j.ophtha.2010.02.020

    View details for Web of Science ID 000283264200002

    View details for PubMedID 20619460

  • Sensitivity and Specificity of Time-Domain versus Spectral-Domain Optical Coherence Tomography in Diagnosing Early to Moderate Glaucoma OPHTHALMOLOGY Chang, R. T., Knight, O. J., Feuer, W. J., Budenz, D. L. 2009; 116 (12): 2294-2299

    Abstract

    To evaluate the sensitivity and specificity of measurements of retinal nerve fiber layer (RNFL) thickness in early to moderate glaucoma using Stratus time-domain and Cirrus spectral-domain optical coherence tomography (OCT; Carl Zeiss Meditec, Dublin, CA).Evaluation of diagnostic test or technology.Fifty-four glaucoma subjects with early to moderate visual field defects and 50 age-matched normal subjects.Three peripapillary RNFL scans of 1 eye of each subject using Stratus and Cirrus OCT.Sensitivity and specificity of average, quadrant, and clock-hour RNFL thickness.The average age+/-standard deviation in the normal and glaucoma groups was 62.9+/-12.7 years (range, 40-84 years) and 67.6+/-11.4 (range, 42-85 years), respectively (P = 0.05). The glaucoma group consisted of 34 early (average mean deviation, -3.20+/-1.22 dB) and 20 moderate (average mean deviation, -8.05+/-1.87 dB) glaucomas. Cirrus OCT sensitivity and specificity for average RNFL abnormal at the 5% level were 83% and 88%, respectively, and at the 1% level were 65% and 100%, respectively. Stratus OCT sensitivity and specificity for average RNFL abnormal at the 5% level were 80% and 94%, respectively, and at the 1% level were 61% and 100%, respectively. For 1 or more abnormal quadrants at the 5% level, the sensitivity and specificity for Cirrus OCT were 98% and 80%, respectively, and at the 1% level were 87% and 92%, respectively. For 1 or more quadrants abnormal at the 5% level, the sensitivity and specificity for Stratus OCT were 96% and 76%, respectively, and at the 1% level were 74% and 94%, respectively. Cirrus OCT sensitivity and specificity using a criterion of 1 or more abnormal clock hours at the 5% level were 100% and 72%, respectively, and at the 1% level were 85% and 94%, respectively. Stratus OCT sensitivity and specificity for 1 or more abnormal clock hours at the 5% level were 98% and 66%, respectively, and at the 1% level were 85% and 90%, respectively.The sensitivity and specificity of various RNFL parameters using the Cirrus OCT for glaucoma with early to moderate visual field defects are excellent and are equivalent to Stratus OCT.

    View details for DOI 10.1016/j.ophtha.2009.06.012

    View details for Web of Science ID 000272579200005

    View details for PubMedID 19800694

  • Comparison of Retinal Nerve Fiber Layer Measurements Using Time Domain and Spectral Domain Optical Coherent Tomography OPHTHALMOLOGY Knight, O. J., Chang, R. T., Feuer, W. J., Budenz, D. L. 2009; 116 (7): 1271-1277

    Abstract

    To determine the agreement between peripapillary retinal nerve fiber layer (RNFL) thickness measurements from Stratus time domain optical coherence tomography (OCT) and Cirrus spectral domain OCT (Carl Zeiss Meditec, Dublin, CA) in normal subjects and subjects with glaucoma.Evaluation of diagnostic test or technology.A total of 130 eyes from 130 normal subjects and subjects with glaucoma were analyzed. The subjects were divided into groups by visual field criteria: normal (n = 29), glaucoma suspect (n = 12), mild glaucoma (n = 41), moderate glaucoma (n = 18), and severe glaucoma (n = 30).Peripapillary RNFL thickness was measured with Stratus Fast RNFL and Cirrus 200 x 200 Optic Disc Scan on the same day in 1 eye of each subject to determine agreement. Two operators used the same instruments for all scans.Student paired t testing, Pearson's correlation coefficient, and Bland-Altman analysis of RNFL thickness measurements.The average age of the glaucoma group was significantly more than that of the normal group: 68.3+/-12.3 years versus 55.7+/-12.1 years, respectively. For Stratus OCT, the average RNFL thickness (mean +/- standard deviation) was 99.4+/-13.2 microm, 94.5+/-15.0 microm, 79.0+/-14.5 microm, 62.7+/-10.2 microm, and 51.0+/-8.9 microm for the normal, suspect, mild, moderate, and severe groups, respectively. For Cirrus OCT, the corresponding measurements were 92.0+/-10.8 microm, 88.1+/-13.5 microm, 73.3+/-11.8 microm, 60.9+/-8.3 microm, and 55.3+/-6.6 microm. All Stratus-Cirrus differences were statistically significant by paired t testing (P<0.001) except for the moderate group (P = 0.11). For average RNFL, there was also a highly significant linear relationship between Stratus minus Cirrus difference and RNFL thickness (P<0.001). Bland-Altman plots showed that the systematic difference of Stratus measurements are smaller than Cirrus at thinner RNFL values but larger at thicker RNFL values.RNFL thickness measurements between Stratus OCT and Cirrus OCT cannot be directly compared. Clinicians should be aware that measurements are generally higher with Stratus than with Cirrus except when the RNFL is very thin, as in severe glaucoma. This difference must be taken into account if comparing Stratus measurements with Cirrus measurements.

    View details for DOI 10.1016/j.ophtha.2008.12.032

    View details for Web of Science ID 000267789900007

    View details for PubMedID 19395086

  • Diagnosing glaucoma progression. International ophthalmology clinics Chang, R. T., Budenz, D. L. 2008; 48 (4): 13-28

    View details for DOI 10.1097/IIO.0b013e31818b63f0

    View details for PubMedID 18936634

  • Calibration of fundus images using spectral domain optical coherence tomography OPHTHALMIC SURGERY LASERS & IMAGING Lujan, B. J., Wang, F., Gregori, G., Rosenfeld, P. J., Knighton, R. W., Puliafito, C. A., Danis, R. P., Hubbard, L. D., Chang, R. T., Budenz, D. L., Seider, M. I., Knight, O. 2008; 39 (4): S15-S20

    Abstract

    Measurements performed on fundus images using current software are not accurate. Accurate measurements can be obtained only by calibrating a fundus camera using measurements between fixed retinal landmarks, such as the dimensions of the optic nerve, or by relying on a calibrated model eye provided by a reading center. However, calibrated spectral domain OCT (SD-OCT) could offer a convenient alternative method for the calibration of any fundus image.The ability to measure exact distances on SD-OCT fundus images was tested by measuring the distance between the center of the fovea and the optic nerve. Calibrated SD-OCT scans measuring 6 X 6 X 2 mm centered on the fovea and the optic nerve were analyzed in 50 healthy right eyes. The foveal center was identified using cross-sectional SD-OCT images, and the center of the optic nerve was identified manually. The SD-OCT scans were registered to each other, and the distances between the center of the optic nerve and fovea were calculated. The overlay of these SD-OCT fundus images on photographic fundus images was performed.Any image of the fundus could be calibrated by overlaying the SD-OCT fundus image, and the measurements were consistent with previously defined calibration methods. The mean distance between the center of the fovea and the center of the optic nerve was 4.32 +/-0.32 mm. The line from the center of the optic nerve to the foveal center had a mean declination of 7.67 +/- 3.88 degrees. Mean horizontal displacement and vertical displacement were 4.27 +/- 0.29 mm and 0.58 +/- 0.29 mm, respectively.The overlay of the SD-OCT fundus image provides a convenient method for calibrating any image of the fundus. This approach should provide a uniform standard when comparing images from different devices and from different reading centers.

    View details for Web of Science ID 000258283000003

    View details for PubMedID 18777875

  • New developments in optical coherence tomography for glaucoma CURRENT OPINION IN OPHTHALMOLOGY Chang, R., Budenz, D. L. 2008; 19 (2): 127-135

    Abstract

    Structural imaging is becoming a powerful adjunct for the diagnosis and progression of glaucoma. There are several competing technologies in this arena. Optical coherence tomography continues to evolve at a fast pace, so it can be challenging to keep up with the latest information. This review covers the recent papers relevant to optical coherence tomography for glaucoma.Retinal nerve fiber layer imaging by optical coherence tomography is reliable. Age, ethnicity, axial length and optic disc size can affect the machine's normative range. Scan quality can be affected by movement, media opacities, myopia and severity of disease. The sensitivity and specificity are variable across multiple studies. Despite this, the technology is beginning to help us understand the structure-function relationship in glaucoma.The next generation optical coherence tomography is around the corner. By understanding the current strengths and limitations of this advancing technology, one can better assess its use in clinical practice.

    View details for Web of Science ID 000253545800008

    View details for PubMedID 18301286

  • Reproducibility of retinal nerve fiber thickness measurements using the stratus OCT in normal and glaucomatous eyes INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Budenz, D. L., Chang, R. T., Huang, X. R., Knighton, R. W., Tielsch, J. M. 2005; 46 (7): 2440-2443

    Abstract

    To determine the reproducibility of Stratus Optical Coherence Tomography (OCT) retinal nerve fiber layer (RNFL) measurements around the optic nerve in normal and glaucomatous eyes.One eye was chosen at random from 88 normal subjects and 59 glaucomatous subjects distributed among mild, moderate, and severe glaucoma, determined by visual field testing. Subjects underwent six RNFL thickness measurements performed by a single operator over a 30-minute period with a brief rest between sessions. Three scans were taken with the high-density Standard RNFL protocol, and three were taken with the Fast RNFL protocol, alternating between scan protocols.Reliability, as measured by intraclass correlation coefficient (ICC), was calculated for the overall mean RNFL thickness and for each quadrant. The ICC for the mean Standard RNFL thickness (and lower 95% confidence interval [CI]) in normal and glaucomatous eyes was 0.97 (0.96 CI) and 0.98 (0.97 CI), respectively. The ICC for the mean Fast RNFL thickness in normal and glaucomatous eyes was 0.95 (0.93 CI) and 0.97 (0.95 CI), respectively. Quadrant ICCs ranged between 0.79 and 0.97, with the nasal quadrant being the least reproducible of all four quadrants, using either the Standard or Fast RNFL program. The test-retest variability ranged from 3.5 microm for the average RNFL thickness measurements in normal eyes to 13.8 microm for the nasal quadrant measurements in glaucomatous eyes, which appeared to be the most variable.Reproducibility of RNFL measurements using the Stratus OCT is excellent in normal and glaucomatous eyes. The nasal quadrant appears to be the most variable measurement. Standard RNFL and Fast RNFL scans are equally reproducible and yield comparable measurements. These findings have implications for the diagnosis of glaucoma and glaucomatous progression.

    View details for DOI 10.1167/iovs.04-1174

    View details for Web of Science ID 000230112800029

    View details for PubMedID 15980233

  • 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

  • Sensitivity and specificity of the StratusOCT for perimetric glaucoma OPHTHALMOLOGY Budenz, D. L., Michael, A., Chang, R. T., McSoley, J., Katz, J. 2005; 112 (1): 3-9

    Abstract

    To determine the sensitivity and specificity of measurements of the retinal nerve fiber layer (RNFL) using the StratusOCT in glaucoma subjects with visual field (VF) defects.Prospective cross-sectional study.One hundred nine normal and 63 glaucoma subjects.Fast RNFL scans were performed in one eye of each patient using the StratusOCT.Sensitivity and specificity of different optical coherence tomography (OCT) criteria for identifying glaucoma subjects with glaucomatous VF defects.Areas under the receiver operating characteristic curves (AROCs) for various OCT parameters.Severity of VF defects in the glaucoma group was distributed between mild (18 subjects), moderate (21 subjects), and severe (24 subjects). The average mean deviation of the glaucoma fields was -8.4 decibels (dB), with a standard deviation of 6.0 dB and a range from -0.14 to -28.0 dB. The sensitivity and specificity using a criterion of average RNFL thickness abnormal at the <5% level were 84% and 98%, respectively. The sensitivity and specificity using a criterion of average RNFL thickness abnormal at the <1% level were 68% and 100%. The sensitivity and specificity of using a criterion of >or=1 quadrants abnormal at the <5% level were 89% and 95%. The sensitivity and specificity of using a criterion of >or=1 quadrants abnormal at the <1% level were 83% and 100%. The sensitivity and specificity of using a criterion of >or=1 clock hours abnormal at the <5% level were 89% and 92%. The sensitivity and specificity of using a criterion of >or=1 quadrants abnormal at the <1% level were 83% and 100%. The AROC for mean RNFL thickness was 0.966. Other high AROC values included the superior quadrant (0.952), inferior quadrant (0.971), inferotemporal clock hour at 7-o'clock (right eye) and 5-o'clock (left eye) (0.959), 6-o'clock hour (0.940), superotemporal clock hour at 11-o'clock (right eye) and 1-o'clock (left eye) (0.935), and 12-o'clock hour (0.924).The sensitivity and specificity of RNFL measurements using the new StratusOCT for glaucoma with manifest VF defects are excellent. The best parameters seem to be >or=1 quadrants abnormal at the or=1 clock hours abnormal at the

    View details for DOI 10.1016/j.ophtha.2004.06.039

    View details for Web of Science ID 000226242800002

    View details for PubMedID 15629813

  • 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

  • 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

  • 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
  • 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
  • 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