En face visualization of the outer choroidal vessels in regions with geographic atrophy

To investigate the relationship between choroidal vessel visibility on en face OCT and the preservation status of outer retinal structures within areas of complete RPE and outer retinal atrophy (cRORA) in age-related macular degeneration (AMD).

In this retrospective observational study, we analyzed 54 eyes from 54 patients with GA due to AMD. All eyes underwent swept-source OCT imaging with 6 × 6 mm volumetric scans centered on the fovea. En face OCT structural images were created using a slab positioned from 64 to 400 μm under Bruch's membrane. Choroidal vessels were classified as highly visible or scarcely visible, while ellipsoid zone (EZ) and retinal pigment epithelium (RPE) were categorized as altered or absent. Area and perimeter of atrophic lesions were measured, and locations were classified as foveal, parafoveal, or perifoveal.

Among the 54 cRORA lesions, 38 eyes (70.4%) exhibited highly visible choroidal vessels, while 16 eyes (29.6%) showed scarcely visible vessels. In areas with highly visible vessels, the EZ was altered in 81.6% of cases, compared to only 12.5% in areas with scarcely visible vessels (p\<0.001). Similarly, lesions with visible vessels were larger and showed a lower proportion of absent RPE (10.5%) than lesions with scarcely visible vessels (62.5%). Interestingly, lesions with highly visible vessels were significantly larger (mean area: 3.30 ± 3.90 mm²) than those with scarcely visible vessels (1.45 ± 2.02 mm², p = 0.024).

Our study reveals an unexpected association between high choroidal vessel visibility on en face OCT and altered rather than absent outer retinal structures in cRORA. This suggests greater heterogeneity within atrophic lesions than previously recognized and challenges conventional understanding of structure-visibility relationships in atrophic AMD.