Location-Specific Thickness Patterns in Intermediate Age-Related Macular Degeneration Reveals Anatomical Differences in Multiple Retinal Layers

Purpose: To examine individual retinal layers' location-specific patterns of thicknesses in intermediate age-related macular degeneration (iAMD) using optical coherence tomography (OCT). Methods: OCT macular cube scans were retrospectively acquired from 84 iAMD eyes of 84 participants and 84 normal eyes of 84 participants propensity-score matched on age, sex, and spherical equivalent refraction. Thicknesses of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer + Henle's fiber layer (ONL+HFL), inner- and outer-segment layers (IS/OS), and retinal pigment epithelium to Bruch's membrane (RPE-BM) were calculated across an 8 × 8 grid (total 24° × 24° area). Location-specific analysis was performed using cluster(normal) and grid(iAMD)-to-cluster(normal) comparisons. Results: In iAMD versus normal eyes, the central RPE-BM was thickened (mean difference ± SEM up to 27.45% ± 7.48%, P < 0.001; up to 7.6 SD-from-normal), whereas there was thinned outer (OPL, ONL+HFL, and non-central RPE-BM, up to -6.76% ± 2.47%, P < 0.001; up to -1.6 SD-from-normal) and inner retina (GCL and IPL, up to -4.83% ± 1.56%, P < 0.01; up to -1.7 SD-from-normal) with eccentricity-based effects. Interlayer correlations were greater against the ONL+HFL (mean |r| ± SEM 0.19 ± 0.03, P = 0.14 to < 0.0001) than the RPE-BM (0.09 ± 0, P = 0.72 to < 0.0001). Conclusions: Location-specific analysis suggests altered retinal anatomy between iAMD and normal eyes. These data could direct clinical diagnosis and monitoring of AMD toward targeted locations.