BackgroundTo investigate the effect of idiopathic epiretinal membrane (ERM) on the retinal-image quality and psychophysical contrast sensitivity function (CSF).MethodsForty-four subjects with diagnosis of idiopathic unilateral ERM were enrolled in this cross-sectional observational clinical study. The fellow unaffected eyes were set as the control group. For retinal-image quality assessment, an Optical Quality Analysis System (OQAS) based on double-pass technique was used to evaluate objective scatter index (OSI) and Strehl ratio. For visual performance, the CSF under photopic condition was measured.ResultsFor retinal-image quality, the result of double-pass device revealed a significant lower Strehl ratio and larger OSI in the ERM eyes compared to the fellow eyes (all P<0.05). For visual performance, the CSF at all spatial frequencies under photopic condition were also significantly degraded in the ERM eyes compared to the fellow eyes (all P<0.05). For the ERM eyes, the reduction of Strehl ratio and CSF was 29.41 and 54.39%, respectively, and the increase of OSI was 164.10% compared to the fellow eyes. Besides, BCVA significantly correlated to the total CSF (ERM eyes, r=-0.53, P<0.001; the fellow eyes, r=-0.467, P=0.002) and Strehl ratio (ERM eyes, r=-0.485, P=0.001; the fellow eyes, r=-0.311, P=0.043) in both of the ERM and the fellow eyes.ConclusionEyes affected with ERM showed poorer retinal-image quality and visual performance than the normal eyes. Retinal-image quality measured by OQAS based on double-pass technique could be useful for assessing the retinal-image quality for ERM-affected eyes, in which retinal scattering was significantly increased.