High-Resolution En Face OCT of the RPE in Geographic Atrophy Captures Patterns Resembling Fundus Autofluorescence

Purpose: Fundus autofluorescence (FAF) identifies distinct hyperautofluorescent (hyperAF) patterns at the margins of geographic atrophy (GA) that predict progression. We investigated whether high-resolution en face optical coherence tomography (OCT) could reveal corresponding reflectivity patterns within the retinal pigment epithelium (RPE). Methods: In this cross-sectional case series, eyes with GA were imaged using commercial green excitation FAF and a prototype high-resolution OCT (2.7 µm axial resolution). Six consecutively acquired OCT volumes were computationally motion-corrected and fused. En face linear-scale OCT images of the RPE were generated by averaging signals within a slab (5.4-11.7 µm anterior to the RPE posterior boundary) corresponding to the RPE cell body. FAF and OCT images were registered, and the spatial correspondence between FAF hyperAF and OCT RPE hyper-reflectivity was assessed qualitatively and quantitatively. Results: Eight eyes of six patients were analyzed. En face OCT of the RPE enabled visualization of reflectivity patterns mirroring established FAF phenotypes, including patchy, diffuse, and banded patterns. Of 94 hyperAF features identified on FAF, 82 (87%) exhibited corresponding hyper-reflectivity on OCT. Conversely, 82 of 121 OCT RPE hyper-reflective features (68%) corresponded to hyperAF on FAF, whereas 39 were OCT-only; 31 of these OCT-only features (80%) were located within the central 3-mm region where macular pigment attenuates visible light. Conclusions: High-resolution en face OCT captures reflectivity patterns in the RPE that correspond to prognostic FAF patterns in GA. Integrating this surrogate for prognostic FAF markers with established OCT outer retinal and vascular biomarkers offers the potential for a more comprehensive assessment of GA progression risk.