Conversion from Intermediate Age-Related Macular Degeneration to Geographic Atrophy in a Proxima B Subcohort Using a Multimodal Approach

Introduction: This retrospective analysis assessed geographic atrophy (GA) progression in fellow eyes from the Proxima B trial intermediate age-related macular degeneration (iAMD) subcohort using high-resolution multimodal imaging anchored on optical coherence tomography (OCT). Methods: Thirty-two patients from the Proxima B iAMD subcohort were assessed; all had GA with no macular neovascularization (MNV) in the contralateral eye. Imaging data, including color fundus photography, fluorescein angiography, near-infrared reflectance, fundus autofluorescence (FAF), and spectral-domain OCT, were obtained. Features preceding progression/conversion to advanced AMD (drusen, reticular pseudodrusen [RPD], MNV, incomplete/complete retinal pigment epithelium and outer retinal atrophy [iRORA/cRORA]) were assessed. Results: Of 30 fellow eyes with available follow-up images, 12 converted to GA (FAF), 2 converted to MNV, and 16 were nonconverters during the review period (median: 17.8 months). iRORA/cRORA features (present in all converters at baseline) were identified on OCT in eyes that progressed to GA. Median time interval from iRORA to cRORA and from cRORA to GA was 7 months each. GA development/progression was either drusen- or RPD-associated (n = 6 each). Eyes with baseline RPD showed faster GA progression versus eyes with drusen (1.49 vs. 0.38 mm2/year). Conclusions: RPD presence was associated with rapid GA lesion enlargement and may provide an early indication of faster GA progression.