Relating Retinal Morphology and Function in Aging and Early to Intermediate Age-related Macular Degeneration Subjects

Abstract

To evaluate relationships between age-related macular degeneration (AMD) morphology on spectral-domain optical coherence tomography (SDOCT) and visual function. Cross-sectional, observational. From the Alabama Study on Early AMD baseline visit, visual acuity, cone-mediated sensitivity, rod-mediated dark adaptation, and SDOCT were obtained in 1 eye per subject with no apparent retinal aging (n= 15), normal aging (n= 15), early AMD (n= 15), and intermediate AMD (n= 46). The volumes of retinal pigment epithelium (RPE)-drusen complex, RPE-drusen complex abnormal thinning, RPE-drusen complex abnormal thickening, and inner and outer retina were calculated in specified regions using semi-automated SDOCT segmentation. Better cone-mediated sensitivity was associated with greater RPE-drusen complex volume (r=0.34, P < .001) and less RPE-drusen complex abnormal thinning volume (r=-0.31, P= .003). Longer rod-mediated dark adaptation time, the duration for rod-mediated sensitivity to recover from photo-bleach exposure, correlated with lower RPE-drusen complex volume (r=-0.34, P= .005) and greater RPE-drusen complex abnormal thinning volume (r= 0.280, P= .023). In 19 eyes with subretinal drusenoid deposits (SDD) vs 47 eyes without SDD, rod-mediated dark adaptation time was longer (mean ± SD 13.5 ± 7.0 vs 10.2 ± 3.1minutes, P= .004), RPE-drusen complex abnormal thinning volume was greater (P < .0001), and visual acuity and cone sensitivity did not differ. Decreased function relates to structural markers on SDOCT in AMD. Because the RPE-drusen complex includes the interdigitation of outer segments and RPE apical processes and SDD in eyes with AMD, slower dark adaptation might be related to structural abnormalities of the RPE, the RPE-photoreceptor interface, or both.