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

The purpose of this study was to characterize the association between geographic atrophy (GA) growth and age-related macular degeneration (AMD) drusen phenotype.

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.

The mean baseline GA area was 1.2 ± 0.8 mm². The overall mean GA growth rate was 1.5 ± 0.9 mm²/year. Group 1 (RPD) showed the fastest progression at 2.56 ± 1.09 mm²/year, significantly higher than Group 2 (LSD, 1.02 ± 0.80 mm²/year) and Group 3 (1.10 ± 0.81 mm²/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.

GA progression is significantly faster in eyes with pure RPD phenotype. Mixed phenotype behaves similarly to LSD, supporting phenotype-specific monitoring and treatment strategies.