To evaluate the utility of preoperative optical coherence tomography (OCT) and multifocal electroretinography (mfERG) in prediction of visual outcomes after idiopathic epiretinal membrane (ERM) surgery.

Retrospective, observational case series.

One hundred eyes of 100 patients with idiopathic unilateral ERM who underwent vitrectomy for ERM removal were retrospectively reviewed. Correlations between preoperative data (OCT and mfERG) and final best-corrected visual acuity (BCVA) were investigated using Pearson correlation analysis. One-way analysis of variance (ANOVA) was used to determine whether final BCVA and mfERG values differed among subgroups varying in photoreceptor integrity status. Receiver operating characteristic (ROC) curve analysis was performed to obtain a cutoff value of the P1 implicit time predicting visual recovery (final BCVA ≥20/25).

BCVA significantly improved, and 65 of 84 eyes (77%) achieved visual recovery of more than 2 Snellen lines after ERM surgery. Final BCVA was significantly correlated with preoperative photoreceptor integrity and P1 implicit time. The area under the ROC (AUROC) curve was statistically significant when P1 implicit time was examined, and the cutoff value for good visual prognosis was 40.81 msec (sensitivity: 72.7%; specificity: 81.3%).

Photoreceptor disruption detected by OCT and P1 implicit time delay on mfERG were significant predictors of poor visual recovery after ERM surgery.