To investigate surgical results for medium-sized (251–400 µm) macular holes (MHs).

This retrospective observational study involved 266 eyes of 262 consecutive patients who underwent internal limiting membrane (ILM) peeling (147 eyes in the ILM peeling group) or inverted ILM flap cover technique (119 eyes in the inverted flap group) for primary medium-sized full-thickness MHs. Macular hole associated with retinal detachment, recurrent MH, and traumatic MH were excluded.

The primary closure rate for overall medium-sized MHs was 100% (119 of 119 eyes) in the inverted flap group, which was significantly higher than that (94.6% [139/147 eyes]; P = 0.010) in the ILM peeling group. Notably, even after adjusting for the minimum MH diameter, presence of high myopia, or preexisting posterior vitreous detachment, the primary closure rate was significantly better in the inverted flap group than in the ILM peeling group (Cochran–Mantel–Haenszel test, overall adjusted P = 0.006, 0.009, 0.005, respectively). The preoperative and postoperative restoration of the outer retinal layers and visual acuity were comparable between the inverted ILM flap and ILM peeling techniques.

Primary closure for medium-sized MHs was significantly superior in the inverted flap group than in the ILM peeling group.