OCT findings and ectopic inner foveal layer stages in unilateral epiretinal membrane with binocular versus monocular metamorphopsia

To compare optical coherence tomography (OCT) findings between patients with unilateral epiretinal membrane (ERM) who perceived metamorphopsia only under monocular viewing conditions and those who perceived metamorphopsia under binocular viewing conditions. This prospective single-center study included patients with unilateral ERM. Best-corrected visual acuity (BCVA), metamorphopsia severity measured using M-CHARTS, OCT findings, and vision-related quality of life (VR-QoL) assessed with National Eye Institute 25-Item Visual Function Questionnaire (VFQ-25) were evaluated. OCT parameters included ectopic inner foveal layer (EIFL) stage, inner and outer retinal cystoid spaces, ellipsoid zone disruption, epiretinal proliferation (EP), and central bouquet abnormalities. Patients were classified into a monocular metamorphopsia (Mono-M) group and a binocular metamorphopsia (Bino-M) group according to the presence of metamorphopsia under binocular viewing conditions. Clinical characteristics and OCT findings were compared between the groups. Sixty-seven eyes from 67 patients were included (Mono-M: 43 eyes; Bino-M: 24 eyes). Age, BCVA, and monocular metamorphopsia scores did not differ significantly between the groups. Among the evaluated OCT findings, only EIFL stage distribution differed significantly, with stage 2 being more frequent in the Bino-M group (p = 0.04). Other OCT findings did not differ between the groups. The VFQ-25 composite scores were significantly higher in the Mono-M group than in the Bino-M group (p = 0.02). Patients with unilateral ERM who perceived metamorphopsia under binocular viewing conditions showed a different distribution of EIFL stages and lower VR-QoL than those with monocular metamorphopsia.