External limiting membrane defects in age-related macular degeneration. The Beijing Eye Study.

To assess the prevalence and associations of external limiting membrane (ELM) defects on optical coherence tomographic (OCT) images in a general population, affected by age-related macular degeneration (AMD) or free of any retinal disease. Using OCT images, we assessed the ELM defect presence in participants of the population-based Beijing Eye Study. The study population consisted of 712 (44.2%) eyes with early AMD, 295 (18.3%) eyes with intermediate AMD, 12 (0.7%) eyes with geographic atrophy and 592 (36.7%) eyes without signs of AMD. ELM defect prevalence increased from 6/592 (1.0%; 95% CI: 0.0, 2.0) in the normal group to 57/712 (8.0%; 95% CI: 6.0, 10.0), 117/295 (39.7%; 95% CI: 34.2, 45.2) and 11/12 (91.7%; 95% CI: 73.7, 100) in the group with early AMD stage, intermediate AMD and late AMD stage, respectively. Higher ELM defect prevalence was spatially associated with higher prevalence of ellipsoid zone (EZ) defects (OR: 929; 95% CI: 291-2964; p < 0.001). In multivariable analysis, higher ELM defect prevalence correlated with higher AMD stage (OR: 2.22; 95% CI: 1.33, 3.71; p = 0.002), higher prevalence of intraretinal hyperreflective foci (iHRFs) superior to the EZ/ELM (OR: 29.7; 95% CI: 8.69-102; p < 0.001), lower prevalence of iHRFs beneath the EZ/ELM (OR: 0.11; 95% CI: 0.04, 0.35; p < 0.001) and higher prevalence of localized interdigitation zone thinnings (IZTs) (OR: 5.66; 95% CI: 3.14, 10.2; p < 0.001). The spatial correlation between ELM defects and EZ defects, the associations of both defect types with a higher occurrence of iHRFs superior to the ELM, the association between an absence of ELM defects and a higher prevalence of iHRFs located inferior to the ELM, and the association between a higher ELM defect prevalence and higher IZT prevalence may suggest the ELM/EZ may act as a barrier for RPE cells migrating into the retina.