Rapid Macular Thinning as a Biomarker for Geographical Atrophy

Purpose: To assess the rate of retinal thinning as a biomarker for incident late-stage age-related macular degeneration (AMD). Methods: This retrospective cohort study included patients (aged ≥ 50 years) with ≥ 3 optical coherence tomography (OCT) macular scans ≥ 6 months apart. Eyes that developed ≥ 250 μm of complete retinal pigment epithelium (RPE) and outer retinal atrophy (cRORA) with associated hypertransmission through Bruch’s membrane on OCT were considered to have developed geographic atrophy (GA). The spatial pattern of macular thinning was assessed using the ETDRS rings centered on the foveola, calculated as a percentage change relative to its baseline value by eye. Results: A total of 201 eyes met inclusion criteria. At last follow-up, 17 eyes developed GA (8.5%) at a median observation of 5.2 (2.4) years. The central subfield (1-mm) and inner ring (3-mm ETDRS subfield) thinned faster in eyes that developed incipient GA (central subfield thickness [CST]: − 1.59% vs. − 0.47% per year, p =0.007; inner ring: − 1.48% vs. − 0.65% per year, p < 0.001), while the outer ring (6-mm ETDRS subfield) thinned less rapidly (− 0.75% vs. − 0.30% per year, p =0.003). Linear regression identified the rate of inner ring thinning as the most significant predictor of GA, with a receiver operating characteristic curve demonstrating a high predictive accuracy (area under the curve [AUC], 0.821; 95% CI, 0.746– 0.896; p < 0.001). Conclusion: Rapid thinning of the inner ETDRS ring is associated with incipient GA. Identifying eyes at risk of late AMD using serial OCT scans would permit personalized monitoring and treatment strategies critical for safeguarding vision.