Zoster Eye Disease Study

PARTICIPANT INCLUSION CRITERIA

To be eligible for study participation, an individual must meet all of the following
criteria:

   1. Ability to understand, and willingness and ability to read and sign, the informed
   consent form.

   2. Ability to understand and follow instructions and study procedures.

   3. Willingness to comply with all study procedures and be available for the duration of
   the study.

   4. Ability to take oral medication, and are willing to adhere to study medication
   regimen.

   5. Age 18 years or older.

   6. Diagnosed with HZO in one eye based on both of these criteria:

      1. History of characteristic unilateral, usually vesicular, HZO rash in the
      dermatomal distribution of cranial nerve V1 or V2.

      2. Medical record documentation of an episode of active dendriform epithelial
      keratitis, stromal keratitis, endothelial keratitis, and/or iritis due to HZO
      within the preceding year. This episode of active anterior segment ocular disease
      may be due to HZO of recent onset (within the preceding 6 months); or chronic HZO
      (with onset six or more months ago); may be new, worsening, or recurrent disease
      after a period of inactivity; and may occur after medication was reduced.

   i. Study participants with chronic HZO must be on a stable treatment regimen and off
   antivirals for at least 30 days before enrollment. Study participants with chronic HZO
   who do not meet this criterion may be rescreened, if they are able to meet this
   criterion within 3 months after the study visit. This is not a requirement for study
   participants with recent onset HZO, who may be enrolled at any time, preferably after
   completing recommended acute antiviral treatment, if prescribed, is completed. They
   can be on variable dose of steroids, and only need to be off oral and topical
   antivirals by the enrollment visit.

   7. For females with reproductive potential, willingness to use highly effective
   contraception (e.g., hormonal contraception, barrier contraception, intrauterine
   device, or abstinence).

PARTICIPANT EXCLUSION CRITERIA

An individual who meets any of the following criteria will be excluded from participation
in this study:

   1. History of immunocompromised status as defined by current CDC contraindications for
   the vaccine against zoster (44).

      1. Study participants who are diagnosed with leukemia, lymphomas or other malignant
      neoplasms affecting bone marrow or lymphatic system, unless leukemia in remission
      and off chemotherapy for at least 3 months.

      2. Study participants who are diagnosed with Acquired Immune Deficiency Syndrome
      (AIDS) or presents with other clinical manifestations of Human Immunodeficiency
      virus (HIV) including CD4 count of ≤ 200 cells/ml.

      3. Study participants on immunosuppressive therapy including:

   i. High-dose corticosteroids (greater than equivalent of prednisone 20 mg/day within 1
   month) ii. Chemotherapy, other than low dose used for treatment of immune-mediated
   diseases within 3 months iii. Study participants receiving recombinant human immune
   mediators and immune modulators, especially antitumor necrosis agents, within 1 month
   prior to enrollment d. Study participants with unspecified cellular immunodeficiency.
   e. Study participants with history of hematopoietic stem cell transplantation.

   2. Medical history of a systemic disease and thought likely to meet one of the exclusion
   criteria listed in exclusion criterion #1 during the 18-month study period.

   3. Renal insufficiency:

      1. Requires dialysis or has history of renal transplant or

      2. eGFR less than 45, determined within 3 months days preceding enrollment.

   4. Allergy or adverse reaction to valacyclovir or acyclovir.

   5. History of vaccination against zoster within one month prior to enrollment. Study
   participants who meet this exclusion criterion may be may be screened and enrollment
   delayed until eligible within 3 months. If the study participant receives the Herpes
   Zoster Subunit vaccine (Recombinant Zoster Vaccine (RZV), Shingrix), rescreening
   should take place one month after the second required dose of the vaccine.

   6. Keratorefractive surgery, other than limbal relaxing incisions or astigmatic
   keratotomies at the time of cataract surgery, within 5 years of enrollment, or
   keratoplasty of the involved eye with zoster.

   7. On systemic antivirals with activity against herpes within the past 30 days, including
   acyclovir, valacyclovir, or famciclovir, for any reason except for treatment of recent
   onset HZO, including investigational drug trial.

   8. History of another condition that may require treatment with one of these three
   antivirals listed above in exclusion criterion #7, during the course of the study;
   study participants who require chronic suppressive antiviral treatment with these
   medications will be excluded.

   9. Sexually active women who are pregnant, nursing, or in their reproductive years who do
   not agree to use contraception during the 1-year treatment period.

10. Incarceration

11. Any condition or circumstance that in the opinion of the study investigator, would
   place the study participant in increased risk or affect his/her full compliance or
   completion of the study.

12. Participation in a clinical study testing a drug, biologic, device or other
   intervention within the last 30 days from enrollment visit. Study participants who
   meet this criterion may be rescreened.