Inclusion Criteria: 1. Age ≥ 18 for Cohorts 1 through 3, and age ≥ 6 years and \< 18 years for Cohort 4. 2. Male patients with clinical diagnosis of XLRS caused by mutations in RS1. 3. Best corrected visual acuity (BCVA) in study eye of 34 to 73 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (corresponding to a Snellen acuity of 20/200 to 20/40). Exclusion Criteria: 1. Pre-existing eye conditions in the study eye that would contribute significantly to an increased risk of visual loss from a subretinal injection. 2. Any intraocular surgery (including laser treatment) in the study eye within 6 months prior or any intraocular surgery anticipated in the study eye during the first 12 months of the study. 3. Treatment in a prior ocular gene or cell therapy study.