AIM: To observe the effects of the different extents of internal limiting membrane (ILM) peeling on the surgical success and anatomical and functional outcomes of idiopathic macular hole (IMH). METHODS: In this retrospective cohort study, 36 patients were reviewed and divided into two groups according to the extent of ILM peeling: group A (18 patients), with the peeling area within one-half of the optic disc macular distance as the radius; group B (18 patients), with the peeling area larger than that of group A but did not exceed the optic disc macular distance as the radius. The main outcomes included the best corrected visual acuity (BCVA), light-adaptive electroretinography, macular hole (MH) closure rate, central macular thickness (CMT), retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness [nine regions based on the Early Treatment of Diabetic Retinopathy Study (ETDRS) ring] before and 1, 3, and 6mo after surgery. RESULTS: The closure rate was 94.4% (17/18) both in groups A and B. The BCVA in both groups improved significantly compared with the preoperative values, but there was no difference between the two groups. The b-wave amplitude of the electroretinogram analysis was significantly improved in both groups compared to that of the preoperative period, with a greater increase in group A than in group B at 6mo (P=0.017). The CMT in both groups gradually decreased after surgery, and there was no difference between the two groups. The RNFL thickness of the temporal outer ring region in group B was significantly lower than that in group A at 3 and 6mo after surgery (P=0.010, 0.032). The GCC thickness of the temporal outer ring region in group B was significantly lower than that in group A at 6mo after surgery (P=0.038). CONCLUSION: Enlarging the extent of ILM peeling doesn’t affect the IMH closure rate and visual acuity recovery, but the greater the extent of peeling, the greater the damage to the inner retinal structures.