Purpose: We aimed to quantitatively evaluate metamorphopsia pre- and postoperatively in patients with idiopathic epiretinal membrane(iERM) using M-CHARTS™ and to evaluate the relationship between morphological changes in retinal layers on optical coherence tomography (OCT) and metamorphopsia scores.Materials and Methods: This prospective study included 42 patients followed in Akdeniz University Hospital Ophthalmology Clinic diagnosed with iERM by fundus examination and OCT between 2020-2022. Detailed ophthalmologic findings, visual acuities, metamorphopsia scores, and OCT parameters of all patients were recorded. The relationship between pre- and postoperative visual acuity, metamorphopsia scores and OCT parameters was investigated. Changes in OCT parameters were compared by evaluating patients with stable or increasing metamorphopsia scores as one group (Group1) and patients with decreasing metamorphopsia scores as the other group (Group 2).Results: In “Group 2,” preoperative Ganglion Cell Layer+Inner Plexiform Layer (Central) (GCL+IPL (C)) was significantly (p:0.028) higher than in “Group 1.”Conclusion: A statistically significant preoperative thickness difference in the OCT parameters of the GCL+IPL (C) layer was associated with the quantitative metamorphopsia complaints of the patients. The thickness of the preoperative GCL+IPL (C) layer can be considered an important indicator of symptoms of metamorphopsia determining functional success after surgery.