To identify characteristics measured by optical coherence tomography (OCT) that are correlated with visual outcome after epiretinal membrane (ERM) removal by pars plana vitrectomy (PPV). Interventional, prospective, randomized case series. One hundred and one eyes of 101 patients with idiopathic ERM underwent PPV for ERM removal. Ophthalmic evaluations included best-corrected visual acuity (BCVA) and Stratus OCT preoperatively at 3 and 6 months postoperatively. Relations between three OCT features including integrity of junction between inner and outer segments of photoreceptors (IS/OS junction), macular thickness, foveal contour and the three visual acuity parameters such as preoperative BCVAs, postoperative BCVAs, and the differences between preoperative and postoperative BCVAs (BCVA differences) were evaluated with respect to time. Eyes with disruption of IS/OS junction had significantly lower postoperative BCVA and BCVA differences than those without disruption (P < .0001, respectively). "Same" (increment or decrement of BCVA up to 1 Snellen line) and "Better" (visual increment of at least 2 Snellen lines) BCVA outcome groups were significantly different with respect to the status of IS/OS junction (P < .005). An increase in the proportion of eyes with photoreceptor disruption was observed at 3 months postoperatively, and this proportion was maintained afterward. Preoperative macular thicknesses showed a positive correlation with BCVA differences, and postoperative macular thicknesses negatively correlated with postoperative BCVA (r > 0.25; P < .05, respectively). Thickness difference and foveal contour were not correlated with the three parameters of visual outcome (P > .05, respectively). Photoreceptor disruption detected by OCT was found to be a predictor of poor visual outcome in eyes with idiopathic ERM, and it was found that this disruption may be irreversible. Thus, early membrane removals may beneficially prevent further progression of photoreceptor damage in ERM patients with photoreceptor disruption.