High-Resolution OCT Profiling of Bruch's Membrane in Extensive Macular Atrophy With Pseudodrusen-Like Appearance and Geographic Atrophy.

Purpose: To characterize Bruch's membrane breaks (BMBs) in extensive macular atrophy with a pseudodrusen-like appearance (EMAP) and geographic atrophy (GA) and to explore their associations with microstructural features within the bed of atrophy, such as basal laminar deposit (BLamD) debris and hyperreflective pyramidal structures (HPSs). Methods: High-resolution optical coherence tomography volumes were obtained from 44 eyes. Quantitative metrics included scan length within atrophy, total BMB length, BMB density per B-scan, and BMB density normalized by atrophy area. Colocalization with microstructural features was assessed per B-scan based on spatial overlap. Results: Patients with GA were significantly older than those with EMAP (80.86 ± 4.75 vs. 61.35 ± 2.62 years; P < 0.001). The atrophy area was larger in EMAP (20.63 ± 14.55 mm²) than GA (7.92 ± 7.27 mm²; P = 0.001). EMAP exhibited a longer BMB length (227.73 ± 311.92 µm vs. 78.00 ± 51.37 µm; P < 0.001) but a lower BMB density per B-scan (1.78 ± 2.43 vs. 5.73 ± 6.75; P < 0.001). Associated features were found in 64.3% of BMBs, more frequently in GA (86.2%) than in EMAP (59.2%; P = 0.006). BLamD debris predominated in EMAP (51.4%), whereas HPS predominated in GA (91%). Conclusions: BMBs associated with EMAP are more likely to be found in widespread BLamD debris areas, while GA shows focal, calcified defects associated with HPS. These findings suggest distinct pathways of BM failure, diffuse in EMAP and focal and mechanical in GA. The clinical implications of these differences and their impact on atrophy progression warrant further study.