Dominant Eye Involvement and Thresholds for Binocular Metamorphopsia in Patients with Unilateral Epiretinal Membrane.

PURPOSE: To evaluate the impact of dominant eye involvement on binocular visual function and vision-related quality of life (VR-QoL), and to determine the monocular metamorphopsia threshold associated with binocular symptom perception in patients with unilateral epiretinal membrane (ERM). METHODS: This prospective single-center study included patients with unilateral ERM. Ocular dominance was determined using the hole-in-card test. Best-corrected visual acuity (BCVA), monocular and binocular metamorphopsia measured with M-CHARTS, aniseikonia, stereopsis, and VR-QoL using VFQ-25 were evaluated. Patients were classified according to whether ERM involved the dominant or non-dominant eye. RESULTS: Sixty-eight patients were enrolled, including 35 patients in the non-dominant eye group and 33 in the dominant eye group. Horizontal binocular metamorphopsia scores were significantly higher in the dominant eye group than in the non-dominant eye group (p < 0.05). No significant differences were observed in BCVA, stereopsis, or VFQ-25 composite scores between the groups. Binocular metamorphopsia scores significantly correlated with VFQ-25 composite scores only in the dominant eye group. Receiver operating characteristic (ROC) analysis demonstrated that a mean monocular metamorphopsia score of 0.55 was the optimal threshold for binocular symptom perception in eyes with dominant eye involvement (AUC = 0.66; 95% CI, 0.48-0.85). CONCLUSION: Dominant eye involvement was associated with greater binocular metamorphopsia and a stronger association between metamorphopsia and VR-QoL in unilateral ERM. A mean monocular metamorphopsia score of ≥ 0.55 may represent a preliminary threshold associated with binocular symptom perception and may help guide future clinical assessment.