The natural history in individuals with severe retinitis pigmentosa (RP) is variable and there remains an unmet need to better understand disease progression in this population. The goal of this study is to determine which visual assessments individuals with RP and low visual acuity can reliably perform and to evaluate the annual decline of visual function in severe RP.

This is a 12-month, single-center, prospective observational study in adults with RP. Approximately 12 subjects will be enrolled into the Observation Period.

The primary objective of this study is to determine which visual assessments RP subjects with low visual acuity can reliably perform. Other objectives are 1) to determine which visual assessments are most sensitive to annual change in RP subjects with low visual acuity, 2) to evaluate adverse events, 3) to evaluate the safety and tolerability of study assessment procedures, and 4) to evaluate the subject's experience in this study, relevance of visual assessments and patient-reported outcome measures, and perception of improvement in visual function.

Inclusion Criteria:

• Subject is able to provide written informed consent and is willing and able to comply with the protocol.
• Subject is ≥ 18 years of age at the time of informed consent.
• Subject has a clinical diagnosis of nonsyndromic retinitis pigmentosa.
• Subject is willing to consent to genetic testing, if not already done.
• Subject has BCVA in the worse eye between hand motion and 35 Early Treatment of Diabetic Retinopathy Study (ETDRS) letter score (approximately ≤ 20/200 Snellen equivalent), inclusive at Screening.
• For subjects who are able to reliably perform kinetic perimetry in the opinion of the Investigator and the assessment provides accurate information, the central visual field diameter (ie, excluding temporal islands) of any visual field diameter is < 20 degrees in the worse eye as measured with the III-4e stimulus using Octopus 900 perimetry at Screening.
• On OCT, inner retinal layers are observed and are retained in the worse eye.

Exclusion Criteria:

• Subject has an eye disease or visual disorder other than retinitis pigmentosa that impairs visual function.
• Subject has any other eye condition, which in the opinion of the Investigator, would preclude an accurate evaluation at any time during the study.
• On OCT, subject has cystoid macular edema in the worse eye in the opinion of the Investigator or is currently receiving treatment for cystoid macular edema in the worse eye.
• Subject has unstable intraocular lens.
• Subject has a clinically significant epiretinal membrane based on the Investigator's judgment that will interfere with the assessments of visual function.
• Subject with a prior vitrectomy in the worse eye will be evaluated on a case-by-case basis by the Investigator to determine if the subject is eligible for the study.
• Subject has any clinically significant unstable medical condition or any clinically significant chronic disease that in the opinion of the Investigator, would limit the subject's ability to complete and/or participate in the study.
• Subject has received treatment with any nonapproved, experimental, or investigational therapy in either eye (systemic, topical, intravitreal) and/or received treatment in an interventional clinical trial for an eye disease or disorder within 90 days or 5 half-lives, whichever is longer, prior to Screening or anticipates the need to receive treatment in an interventional clinical trial during their participation in this study.
• Subject has previously received cell therapy, gene augmentation therapy, genome editing therapy, or any subretinal administered therapy for an eye disease or disorder or anticipates the need for these therapies during their participation in this study.
• Subject has previously received LUXTURNA (voretigene neparvovec-rzyl) or anticipates the need for this therapy during their participation in this study.
• Subject is in the opinion of the Investigator unsuitable in any other way to participate in this study.

Retinitis pigmentosa subjects with low visual acuity