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

Overview

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.

Age-related macular degeneration (AMD) is a leading cause of blindness worldwide, with geographic atrophy (GA) representing the advanced, untreatable form of the disease. GA leads to progressive degeneration of retinal cells critical for vision, resulting in irreversible vision loss and a significant impact on patients' quality of life. Despite the prevalence of GA, treatment options remain limited. Current therapeutic strategies focus on slowing the enlargement of atrophic regions, but clinical trials have faced challenges in demonstrating clear patient benefits. In clinical practice, GA progression is often evaluated by measuring the area of atrophy on retinal imaging, such as fundus autofluorescence (FAF) and, more recently, optical coherence tomography (OCT). These structural biomarkers are used in clinical trials to assess the efficacy of new drugs, with the FDA accepting a reduction in the rate of GA enlargement as a successful outcome. However, these structural metrics often fail to correlate with functional vision loss, leaving patients and physicians disappointed by treatments that may stabilize GA progression without improving their visual outcomes. The ellipsoid zone (EZ), a hyperreflective layer visualized on OCT, represents the structural integrity of photoreceptors-cells responsible for converting light into visual signals. In patients with one or more GA lesions, OCT imaging shows that the EZ is typically absent within the GA, while the EZ in the perilesional zone may be attenuated or damaged. Perilesional EZ loss is thought to represent the area at highest risk for future vision loss. With the FDA approval of photoreceptor preservation as an endpoint for GA trials, there has been significant interest in measuring EZ loss from OCT scans. Drug approval will now focus on the prevention of EZ loss in the perilesional areas rather than GA area expansion. However, it is important to establish whether the absence of the EZ truly indicates photoreceptor damage and whether there is a functional correlation between EZ loss and visual sensitivity. Adaptive Optics and microperimetry are two modalities that can help address this. This sub-study is a pilot comparative imaging study. In addition to the imaging procedures collected for the main COCO GA study \[NCT05961332\], participants will have the following study images obtained: * Spectralis OCT (if applicable), * visual acuity, * ocular biometry, which is a non-invasive eye test using a machine called an IOL master, * microperimetry, and * Adaptive Optics Scanning Light Ophthalmoscopy (AOSLO)