Adaptive Optics Scanning Light Ophthalmoscopy (AOSLO) and Microperimetry (MP) Sub-study

This research sub-study is to evaluate if combining images from Optical Coherence Tomography (OCT) scans with Adaptive Optics Scanning Light Ophthalmoscopy (AOSLO) and Microperimetry (MP) could show a link between structural changes in the back of the eye and vision. 10 participants that were enrolled in the COmparison of Clarus and Optos Ultrawide Field Imaging Systems for Geographic Atrophy study \[NCT05961332\] will be approached to enroll. Participants may complete OCT imaging and initial assessments during an initial visit and may return for additional procedures, including microperimetry and AOSLO imaging, within a window of up to 4 weeks.

Inclusion Criteria (from the main study): * 50 years or older and may be either male or female and may be of any race * Established diagnosis of geographic atrophy (GA) due to age-related macular degeneration (AMD) * GA characteristics: GA area of between 1.25 mm² and 23 mm², with seventy percent of eyes having GA area ranging from 2.5 mm² to 17.5 mm². GA may be unifocal or multifocal. GA may be subfoveal or extrafoveal, with twenty-five percent of eyes having subfoveal GA. The presence of concurrent peripapillary atrophy will not exclude participants from participation * Willing to participate as evidenced by signing the written informed consent Additional Sub-study Inclusion Criteria: * Early-stage GA defined as * GA area of between 1.25 mm2 and 23 mm2 * GA may be unifocal or multifocal * GA may be subfoveal or extrafoveal * Concurrent peripapillary atrophy will not exclude participant from participation * Phakic and pseudophakic participants are eligible for enrollment, with phakic participants prioritized when feasible. Exclusion Criteria (from the main study): * Unable to tolerate ophthalmic imaging * Presence of neovascular AMD on optical coherence tomography (OCT) as confirmed by an ophthalmologist * Presence of significant media opacity preventing adequate retinal imaging * Presence of concurrent retinal disease which may confound assessment Additional Sub-study Exclusion Criteria: * Ocular media opacity or other condition(s) that, in the opinion of the investigators, may preclude imaging. * Individuals who, in the opinion of the investigator, are unable to tolerate study procedures or comply with study requirements. * Prior or current treatment with intraocular injections for geographic atrophy (e.g., pegcetacoplan \[Syfovre\] or similar therapies) is not permitted.