KB803-EYE-01 is a Phase 3 double-blind, randomized, placebo-controlled, crossover study to evaluate the safety and efficacy of KB803 versus matched placebo in pediatric and adult subjects with recurrent corneal abrasions due to dystrophic epidermolysis bullosa (DEB).

Subjects participating in the Sponsor's natural history study (protocol NHS) for at least 12 weeks and that meet all other eligibility criteria will be randomized 1:1 to receive ophthalmic administration of B-VEC three times a week or placebo three times a week for the first 12 week intervention period. During the second 12-week intervention period subjects will be crossed-over to receive the alternative Investigational Product (IP) for an additional 12 weeks. IP will be administered in the home setting by a trained designee. The Investigator (or designee) will contact subjects (or their parent/legal guardian) to assess for any adverse events or changes in medications, treatments, or procedures. Subjects (or their parent/legal guardian) will complete weekly symptom diaries and monthly questionnaires to document corneal abrasion symptoms and frequency and gauge overall subject (or parent/legal guardian) impressions of disease severity and disease/symptom changes during the study.

Inclusion Criteria:

1. The subject and/or their parent/legal guardian must provide informed consent/assent and must be able to and willing to follow study procedures and instructions.
2. Age 6 months or older at time of informed consent/assent.
3. Confirmed diagnosis of DEB with a mutation in the COL7A1 gene.
4. Meets minimum corneal abrasion symptom frequency in the NHS study.

Exclusion Criteria:

1. Initiation of any new treatment regimen or change in treatment for ocular disease during the run-in period except for preservative free topical antibiotics or artificial tears/lubricants associated with standard of care treatment of corneal abrasions.
2. Treatment with an investigational agent or off-label ophthalmic use of an approved product during the run-in period or planned use during the study (Exceptions may be approved by the medical monitor on a case-by-case basis).
3. Any condition that, in the opinion of the Investigator, would impact the completion of all study-related assessments, interfere with the administration of study drug, and/or poses an additional risk to the subject.
4. Women who are pregnant or nursing.
5. Subject who is unwilling to comply with contraception requirements per protocol.
6. Subject is known to be noncompliant or is unlikely to comply with the requirements of the study protocol in the opinion of the Investigator.