Comparison of the Use of Internal Limiting Membrane Flaps Versus Conventional ILM Peeling on Post-Operative Anatomical and Visual Outcomes in Large Macular Holes

Background Idiopathic full-thickness macular hole (iFTMH) closure rates following conventional vitrectomy, gas tamponade and internal limiting membrane (ILM) peeling decrease when the minimum linear diameter (MLD) ≥ 500 microns. ILM flap creation has been proposed to improve closure in larger holes. This study evaluated the anatomical and functional impact of ILM flap introduction to routine practice in iFTMH ≥500 microns. Methods Retrospective, interventional analysis of prospectively collected data of 191 eyes from consecutive surgeries for primary iFTMH ≥500 microns performed by two surgeons between June 2018 and June 2022, during which both surgeons replaced ILM peeling with ILM flap creation. Post-operative best-corrected visual acuity (BCVA) and anatomical closure were compared between Group 1 (ILM peel) and Group 2 (ILM flap) in an intention-to-treat analysis. Results Rates of iFTMH closure were greater in the ILM flap group (77/80; 96.3%) than the ILM peel group (94/110; 85.5%) (OR = 4.37, 95% CI = 1.23–15.55, p = 0.023). A non-significant increase in post-operative BCVA improvement was observed in the ILM flap group ( p = 0.084). There was no statistically significant difference in final BCVA ( p = 0.83). Multivariate logistic regression found only MLD (OR = 0.993, 95% CI = 0.989–0.997, p = 0.001) and ILM flap group (OR = 5.795, 95% CI = 1.313–25.570, p = 0.020) predicted primary closure. Conclusion ILM flap creation improves closure rates in larger holes and should be considered routinely in iFTMH ≥500 microns. Whether ILM flaps affect post-operative visual function remains uncertain.