Relationship between macular thickness and mesopic visual acuity in older subjects without retinal disease

Abstract

Purpose Impaired mesopic visual acuity (VA) is a risk factor for incident early age‐related macular degeneration 3 years later. However, there is a lack of data on the retina structure‐function relationship in healthy eyes. In this study, the correlations of macular thicknesses with photopic and mesopic VA were analyzed in young and older subjects without retinal disease. Methods Retinal thickness was measured by spectral‐domain optical coherence tomography in one eye of 40 young and 41 older healthy subjects with best corrected VA of 20/20. Macular thicknesses measurements from complete and inner and outer retinal‐segmentation (IRS and ORS) of the central fovea, inner ring, outer ring, and ganglion cell complex were used in analyses. Best‐corrected distance VA was measured using HC and LC logMAR charts under photopic and mesopic (1 cd/m2) luminance conditions. The decrease in mesopic VA when compared to photopic VA (low luminance VA deficit) was registered. Pearson correlation followed by multiple forward stepwise regression analyses were performed in each age group. Results In the older group, the macula was thicker in the ORS of the central fovea and inner ring, and thinner in the IRS of inner ring and outer ring (all, P < 0.01). Mean photopic and mesopic HC‐VA and LC‐VA, and mean HC‐low luminance VA defict were significantly worse in the older group (all, P < 0.01). Significant correlations were detected only in the older group. Multiple regression analysis showed that ORS thickness of inner ring was independent contributor to mesopic LC‐VA (r = 0.40, P = 0.01) and the complete thickness of central fovea was independent contributor to HC‐ and LC‐low luminance VA deficit (r = 0.45, P = 0.003; r = 0.32, P = 0.04