Natural History of Geographic Atrophy Secondary to Age-Related Macular Degeneration: Results from the Prospective Proxima A and B Clinical Trials.

Abstract Purpose To better characterize visual function decline and geographic atrophy (GA) progression secondary to age-related macular degeneration (AMD). Design Proxima A (NCT02479386) and Proxima B (NCT02399072) were global, prospective, non-interventional, observational clinical trials. Participants Eligible patients were aged ≥50 years. Patients in Proxima A had bilateral GA without choroidal neovascularization (CNV) in either eye (N=295). Patients in Proxima B had GA with no CNV in the study eye and CNV±GA in the fellow eye (fellow eye CNV cohort, n=168); or GA with no CNV in the study eye, without CNV/GA in the fellow eye (fellow eye intermediate AMD cohort, n=32). Methods Changes in visual function and imaging/anatomic parameters were evaluated over time using a Mixed Model for Repeated Measurement (MMRM) accounting for key baseline characteristics. Main Outcome Measures Pre-specified endpoints included change in GA area from baseline, best corrected visual acuity (BCVA) score assessed by ETDRS, and BCVA under low-luminance conditions (LLVA). Results At 24 months, the adjusted mean (standard error; SE) change in GA lesion area from baseline was 3.87 (0.15) mm2 in participants with bilateral GA (Proxima A), 3.55 (0.16) mm2 in the fellow eye CNV cohort (Proxima B), and 2.96 (0.25) mm2 in the fellow eye intermediate AMD cohort (Proxima B). GA progression was greater in patients with baseline non-subfoveal (vs. subfoveal) GA lesions, and tended to increase as baseline low-luminance deficit increased (Proxima A; Proxima B, all patients). Conversion to GA or CNV in the fellow eye occurred in 30% and 6.7% of participants, respectively, in the Proxima B intermediate AMD cohort at month 12. Adjusted mean (SE) changes in BCVA and LLVA (ETDRS letters) in the study eye from baseline to 24 months: −13.88 (1.40) and −7.64 (1.20) in Proxima A, −9.49 (1.29) and −7.57 (1.26) in the Proxima B fellow eye CNV cohort, −11.48 (3.39) and −8.37 (3.02) in the Proxima B fellow eye intermediate AMD cohort, respectively. Conclusions The prospective Proxima A and B studies highlight the severe functional impact of GA and the rapid rate of GA lesion progression over a 2-year period, including in patients with unilateral GA at baseline