To investigate the anatomical and visual outcomes of inverted internal limiting membrane (i-ILM) flap insertion versus single-layered i-ILM flap covering in highly myopic macular holes (HMMHs) associated with macular retinoschisis (MRS).A retrospective study compared 23G vitrectomy with i-ILM flap insertion (30 eyes) or covering (31 eyes) in HMMH patients. Pre- and postoperative optical coherence tomography images and best-corrected visual acuity (BCVA) were evaluated. Macular hole schisis (MHS) was classified into three types based on the extent of outer layer schisis. Regression analysis identified predictors of closure rate and postoperative BCVA.The baseline data of the two groups were matched, including BCVA, axial length, and minimum linear diameter, except for a higher hole height in insertion group (P=0.038). After a mean follow-up of 11.7 months, type I closure rates were 83.3% (25/30) in the insertion group and 90.3% (28/31) in the covering group (P=0.335), respectively. The intact external limiting membrane in the covering group (7/28) was higher compared to the insertion group (1/28) finally (P=0.026). Final BCVA improved significantly in both groups (P<0.001), the BCVA was better in closed HMMHs in the covering group (P=0.011). Multivariate linear regression analysis revealed that preoperative BCVA (β=0.386, P=0.001) and MHS stage (β=0.309, P=0.004) were independent predictive factors for the final BCVA.The single-layered i-ILM flap covering favored foveal structure recovery and provided a better visual prognosis in closed HMMHs compared with insertion. The preoperative BCVA and MHS stage were independent predictors of visual outcomes in patients with HMMHs.