Objective: To investigate the morphological changes detected by spectral domain optical coherence tomography (OCT) and their relevance to vision in patients with idiopathic macular epiretinal membranes (IMEM). Methods: This is a retrospective study. OCT recorded 37 eyes with stage 3 and below IMEM according to the 4-level grading system based on OCT images among 35 patients. We managed to obtain thickness of all retina layers in three concentric circular regions with a diameter of 1 mm, 3 mm and 6 mm across macular fovea with the help of a third-party software. Plus we divided all 37 eyes into two groups according to whether there were cystic changes in the inner nuclear layer (INL). Multiple linear regression analyses were performed between thickness of all retina layers and current minimum resolution angle in logarithmic (logMAR) best corrected visual acuity (BCVA). The difference of BCVA between groups with cystic changes and without was also compared. Thus, the relationships between visual acuity and thickness of retina layers, cystic changes in INL were analyzed. Results: Multiple linear regression analyses revealed that thickness of both retina nerve fiber layer (RNFL) and inner nuclear layer have positive correlation with logMAR BCVA in the region with a diameter of 1 mm (P<0.05), while in regions of a diameter of 3 mm and 6 mm, only INL thickness remained positively relevant (all P<0.05). There were significant differences in BCVA and thickness of INL between groups with INL cystic changes and without (all P<0.05). Conclusion: Current visual acuity among preoperative IMEM patients was mostly associated with thickness of RNFL and INL. Cystic change in INL layer may be a good indicator of INL thickening and was visually correlated. Those with this change tend to have worse vision.