Internal limiting membrane flap versus conventional peeling for idiopathic full thickness macular holes: a registry analysis of 2990 eyes

Background: To compare the anatomical and functional outcomes of internal limiting membrane (ILM) flap and conventional ILM peeling in idiopathic full-thickness macular holes (FTMHs). Methods: Retrospective cohort study of all eyes treated with vitrectomy and ILM peeling (ILM-P) with or without ILM flap (ILM-F) for primary idiopathic FTMH repair in the Australian and New Zealand Society of Retinal Specialists (ANZSRS) Registry between 2006 and 2023. Propensity score weighting and multivariable regression analysis adjusted for baseline characteristics and covariates, including surgeon grade, lens status, and follow-up duration, were used to evaluate hole closure rate and best corrected visual acuity (BCVA) change at 3 months. Results: Two thousand nine hundred ninety eyes of 2905 patients were included (mean age 69 ± 9 years). One Hundred Ninety-nine eyes underwent ILM-F and 2871 underwent ILM-P. On weighted multivariable regression analysis, ILM-F showed higher odds of hole closure compared to ILM-P (OR = 2.97, 95% CI: 1.08–8.20, p = 0.04). The adjusted closure rate was > 95% across all hole sizes in the ILM-F group, while only falling below 90% for X-large + holes (> 550 μm) in the ILM-P group. No significant difference in BCVA gain was observed between the two groups at 3 months (p = 0.08). The effects of ILM-F compared to ILM-P were consistent across all hole sizes. Conclusions: Although the ILM-F technique was more effective in idiopathic FTMH closure, visual acuity outcomes were comparable to conventional ILM peeling. These findings suggest that ILM-F is not required for the treatment of small and medium FTMHs.