RecruitingPhase 2Biological interventionA Study to Optimize Subretinal Surgical Delivery and to Evaluate Safety and Activity of Opregen in Participants With Geographic Atrophy Secondary to Age-Related Macular Degeneration (GAlette); Adaptive Optics (AO) Retinal Imaging Substudy in Association With Study GR44251This study will evaluate the success and safety of subretinal surgical delivery as well as the preliminary activity of OpRegen in participants with geographic atrophy (GA) secondary to age-related macular degeneration (AMD). All endpoints are assessed for the study eye unless otherwise indicated. The substudy will evaluate the operational feasibility and scientific interpretability of incorporating AO retinal imaging using the EarlySight Cellularis® Discovery device. Participants who have fulfilled the eligibility requirements for the parent study and meet the substudy's eligibility criteria will have the option to participate in the substudy. The EarlySight Cellularis® Discovery device will be used only as an assessment tool and data obtained from this device will not be used to guide clinical care or influence clinical outcomes for participants.