Association Between Trends in Geographic Atrophy Growth and Age-related Macular Degeneration Drusen Phenotype

Background and Objective: The purpose of this study was to characterize the association between geographic atrophy (GA) growth and age-related macular degeneration (AMD) drusen phenotype. Patients and Methods: This retrospective cohort study included 59 eyes from 47 patients over 55 years with GA, followed for up to 5 years. Eyes with poor-quality imaging, irregular follow-up, or exudation were excluded. Based on multimodal retinal imaging, eyes were classified into three groups: Group 1 (reticular pseudodrusen [RPD]), Group 2 (large soft drusen [LSD]), and Group 3 (mixed RPD and LSD). Fundus autofluorescence (FAF) images were analyzed from baseline to 60 months. GA lesion area and growth rate were measured semi-automatically using Region-Finder (Heidelberg Engineering) and compared across groups over time. Results: The mean baseline GA area was 1.2 ± 0.8 mm 2 . The overall mean GA growth rate was 1.5 ± 0.9 mm 2 /year. Group 1 (RPD) showed the fastest progression at 2.56 ± 1.09 mm 2 /year, significantly higher than Group 2 (LSD, 1.02 ± 0.80 mm 2 /year) and Group 3 (1.10 ± 0.81 mm 2 /year) ( P < .005). No significant difference was observed between Groups 2 and 3 ( P = .28). These differences remained consistent at months 12, 24, 36, 48, and 60. Conclusion: GA progression is significantly faster in eyes with pure RPD phenotype. Mixed phenotype behaves similarly to LSD, supporting phenotype-specific monitoring and treatment strategies.