Key Inclusion Criteria: Part 1: * Participants with genetically confirmed diagnosis of XLRP (with RPGR mutation). * Participant with active disease clinically visible within the macular region in both eyes. Part 2: \- Participant with mean total retinal sensitivity in the study eye as assessed by microperimetry ≥ 0.1 dB and ≤8 dB. Key exclusion Criteria: Parts 1 and 2: * Participant with history of amblyopia in either eye. * Participated in a gene therapy trial previously or a clinical trial with an investigational drug in the past 12 weeks or received a gene/cell-based therapy at any time previously. NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.