Optimizing Surgical Timing in Idiopathic Epiretinal Membrane: Identifying Cutoffs for Preoperative Visual Acuity and Metamorphopsia

Purpose: To identify prognostic factors for postoperative visual acuity (VA) and metamorphopsia outcomes in patients with idiopathic epiretinal membrane (iERM) and to establish clinically meaningful cutoff values to guide surgical timing. Methods: This retrospective study analyzed 72 eyes from 66 patients who underwent pars plana vitrectomy with membrane peeling. Preoperative and 12-month postoperative best-corrected VA (BCVA), metamorphopsia score (META-score), and optical coherence tomography (OCT) biomarkers were evaluated using multivariate regression and receiver operating characteristic (ROC) curve analyses. Results: At 12 months, both BCVA and META-score significantly improved (both P < 0.001). Multivariate analysis identified preoperative BCVA (β = 0.719, P < 0.001), presence of ectopic inner foveal layer (EIFL) (P = 0.046), iERM stage (P = 0.020), and ganglion cell-inner plexiform layer (GCL-IPL) thickness (P = 0.007) as independent predictors of postoperative BCVA. The preoperative META-score was the sole predictor for postoperative metamorphopsia (β = 0.480, P < 0.001). ROC analysis identified optimal cutoffs for predicting poor outcomes: a preoperative BCVA > 0.5 LogMAR (AUC = 0.850) and a META-score > 2.74 (AUC = 0.990). Conclusion: Preoperative functional status (BCVA and META-score) are the primary determinants of surgical outcomes. Inner retinal biomarkers, particularly GCL-IPL thickness, provide independent predictive value. The established cutoffs (BCVA > 0.5 LogMAR; META-score > 2.74) offer objective, data-driven guidance for surgical decision-making and managing patient expectations.