Background To determine whether the internal limiting membrane (ILM) insertion technique is as effective as the inverted ILM flap technique for the initial surgical treatment of eyes with large idiopathic macular holes (MHs).

Methods This retrospective, non-randomised, comparative clinical study included 41 eyes with large MHs (minimum diameter >500 µm) that were treated using the ILM insertion technique or the inverted ILM flap technique. The hole closure rate, postoperative best corrected visual acuity (BCVA) and swept source optical coherence tomography findings were analysed at 6 months after surgery.

Results There were 15 and 26 eyes in the insertion and inverted flap groups, respectively. Hole closure was achieved in all eyes. The mean final BCVA was better in the inverted flap group than in the insertion group (0.527 vs 0.773, p=0.006), although significant postoperative improvements were observed in both groups (p<0.001). Postoperative foveal discolouration was more common in the insertion group than in the inverted flap group (86.7% vs 7.7%, p<0.001). Complete resolution of ellipsoid zone and external limiting membrane defects was observed in 7 and 18 eyes, respectively, in the inverted flap group; in contrast, complete resolution was not observed in any of the eyes in the insertion group (p=0.035 and p<0.001, respectively).

Conclusion The ILM insertion technique may be as effective as the inverted ILM flap technique for the closure of large MHs. However, the latter technique results in better recovery of photoreceptor layers and, consequently, better postoperative visual acuity.