Purpose To investigate the clinical importance of ectopic inner foveal layer (EIFL) grading (mild to severe) in patients diagnosed with idiopathic epiretinal membrane (iERM) and had pars plana vitrectomy (PPV) with solely ERM peeling. Materials and methods Patients diagnosed with iERMs who had undergone PPV including only ERM peeling were enrolled in the study, and follow-up findings were recorded at baseline, and at 3, 6, 12 months and final examinations. EIFL was categorized into four grades, from mild to severe. Pre- and postoperative anatomical changes were measured using spectral domain optical coherence tomography (SD-OCT) imaging. The association between EIFL and other SD-OCT parameters with best-corrected visual acuity (BCVA) was assessed before and after PPV surgery. Results One-hundred thirty-eight eyes of 106 patients with mild to severe EIFL were included in the study. Higher EIFL thickness was significantly correlated with lower baseline (r = 0.575, p = 0.020) and final BCVA (r = 0.748, p = 0.001). Although EIFLs continued in advanced-stage cases (stage 3 and 4) (64 eyes [82%]) at the final visit, it was observed in 8 eyes (23%) in the early stage (stage 2) of iERMs. A strong positive correlation was found between EIFL thickness and recurrence rate of ERM (r = 0.876, p < 0.001). Recurrence of ERM was detected in 27 eyes; 2 (7%) at stage 1, 3 (9%) at stage 2, 10 (23%) in stage 3, and 12 (33%) in stage 4 (p < 0.001). Conclusion A negative association was found between the severity of EIFL and postoperative anatomical and visual recovery. In terms of surgical timing, early stages (stages 1 and 2) may be preferred for providing good anatomical and visual recovery and a low recurrence rate following surgery.