Effects of inverted internal limiting membrane technique and insertion technique on outer retinal restoration associated with glial proliferation in large macular holes

Purpose: To compare the effects of inverted internal limiting membrane (ILM) flap technique and ILM insertion technique for large macular hole (MH) on glial proliferation, retinal outer layer restoration, and visual function. Methods: This retrospective, observational study included 25 eyes with large MH (minimum diameter, ≥ 400 μm) treated using the inverted ILM flap or insertion technique. The inverted flap group was defined as flipping the ILM upside down on the MH (13 eyes) and the insertion group as inserting multiple ILM layers into the MH (12 eyes). Results: Glial proliferation in the photoreceptor layer at 1 month and the final visit was significantly less frequent in the inverted flap group than in the insertion group (61.5% vs. 100%, p = 0.039; 23.1% vs. 100%, p = 0.001). The mean postoperative external limiting membrane defect was 140.4 ± 286.2 μm in the inverted flap group, significantly narrower than that in the insertion group (364.6 ± 181.6 μm; p = 0.016). The mean postoperative ellipsoid zone defect was 235.3 ± 214.2 μm in the inverted flap group, which was almost significantly narrower than that in the insertion group (496.3 ± 445.6 μm; p = 0.068). The change in the best-corrected visual acuity was significantly better in the inverted flap group than that in the insertion group (+ 18.5 vs. + 9.0 letters). Conclusion: Compared with patients treated with the insertion technique, those treated with the inverted ILM flap technique had significantly less glial proliferation at the photoreceptor space, more preferable outer retinal formation, and better visual improvement.