Temporal inverted internal limiting membrane flap technique versus conventional internal limiting membrane peeling technique for large macular holes: a retrospective comparative study

Abstract Background Full-thickness macular holes (FTMHs) larger than 400 µm remain a surgical challenge with suboptimal closure rates when treated with conventional internal limiting membrane (ILM) peeling. The temporal inverted ILM flap technique has emerged as a promising alternative, yet direct comparisons—particularly regarding hole-size-specific outcomes and outer retinal microstructural recovery—remain scarce. This study aimed to compare the functional, anatomical, and morphological outcomes of these two surgical approaches. Methods This retrospective study included 32 patients with large idiopathic FTMHs (> 400 µm) who underwent surgery between 2020 and 2024. Patients were divided into two groups: conventional ILM peeling (Group 1, n = 16) and temporal inverted ILM flap technique (Group 2, n = 16). All procedures were performed by a single experienced surgeon. Best-corrected visual acuity (BCVA), MH closure rate, closure configuration, macular hole index (MHI), and outer retinal layer parameters including ellipsoid zone (EZ) and external limiting membrane (ELM) integrity were assessed using spectral-domain optical coherence tomography (SD-OCT) at baseline and 12 months postoperatively. Results Baseline characteristics were comparable between groups (all p > 0.05). Both groups showed significant postoperative BCVA improvement (p < 0.05). At 12 months, BCVA was significantly better in Group 2 (0.38 ± 0.32 vs. 0.71 ± 0.46 logMAR, p = 0.039). Overall primary closure rates were 100% vs. 75.0% (p = 0.101). Subgroup analysis by hole size revealed that in eyes with minimum MH diameter ≥ 550 µm, the closure rate was significantly higher in Group 2 (100%, 8/8) compared with Group 1 (33.3%, 2/6; p = 0.015); both groups achieved 100% closure in holes of 400–549 µm. Postoperative EZ defect size was significantly smaller in Group 2 (539.12 ± 618.09 vs. 1028.62 ± 606.93 µm, p = 0.039), with approximately twice the degree of outer retinal layer recovery. Conclusions The temporal inverted ILM flap technique was associated with superior BCVA, better outer retinal layer recovery, and significantly higher closure rates in eyes with minimum MH diameter ≥ 550 µm. These findings suggest it should be the preferred surgical approach for very large macular holes. Trial registration Not applicable (retrospective study).