Relationship between Myopia Severity and Macular Retinal Thickness on Visual Performance under Different Lighting Conditions

To evaluate the relationship between both spherical equivalent (SE) and retinal thickness (RT) on best-corrected visual acuity (BCVA) among young Asian adult men under photopic, mesopic, and simulated night-vision goggle (NVG) lighting conditions. Community-based cross-sectional study. Total of 698 myopic and 148 emmetropic subjects. All participants underwent a complete ophthalmic examination and color fundus photography. BCVA and subjective refraction were assessed under standardized photopic, mesopic, and simulated NVG lighting conditions. Retinal thickness in various Early Treatment Diabetic Retinopathy Study (ETDRS) subfields was measured using spectral-domain OCT using a standardized protocol. Univariate and multiple linear regression analyses were performed to assess the relationship between BCVA and both SE and RT. Relationship between BCVA and both SE and RT. The mean age of all subjects was 21.1 years, with mean SE of −8.44 diopter (D) among the myopic subjects (range, −3.75 D to −23.0 D) and +0.10 among the emmetropic subjects (range, −0.49 D to +1.00 D). BCVA worsened progressively with increasing myopia under all lighting conditions (standardized coefficient −0.581 under photopic conditions, P < 0.001). RT was thickest among participants with LogMAR VA ≤0.00, and became thinner in the groups including those with VA >0.00 to ≤0.10 and >0.10 (mean inner subfield RT: 342.7 μm vs. 338.1 μm vs. 331.0 μm, respectively, P < 0.001) under all lighting conditions. When multiple linear regression was performed, higher degrees of myopia and decreasing RT were associated with reduced BCVA (all P < 0.05). For each diopter increase in myopia, mean BCVA decreased by 0.01 LogMAR in photopic conditions and 0.02 LogMAR in mesopic conditions (both P < 0.001). The mean BCVA reduced by 0.05 LogMAR (P = 0.003) and 0.04 LogMAR (P = 0.037), under photopic and scotopic lighting conditions respectively, for each 100-μm decrease in RT. Both the severity of myopia and macular RT independently affect visual performance under photopic, mesopic, and simulated NVG conditions.