Vitrectomy in Small idiopathic MAcuLar hoLe (SMALL) study: conventional internal limiting membrane peeling versus inverted flap

Background: To compare conventional internal limiting membrane (ILM) peeling versus inverted flap technique in small idiopathic macular hole. Methods: Retrospective, multicentre cohort study including consecutive eyes with a ≤250 μm idiopathic macular hole treated with primary vitrectomy. The primary outcome was best-corrected visual acuity (BCVA) change and macular hole closure rate. Closure patterns on optical coherence tomography (OCT) and rates of external limiting membrane (ELM) and ellipsoid zone (EZ) recovery were considered as secondary outcomes. Results: A total of 389 and 250 eyes were included in the conventional ILM peeling group and in the inverted flap group, respectively. Hole closure rate was comparable between the two groups (98.5% in the ILM peeling group and 97.6% in the inverted flap group). Mean BCVA was comparable between the two groups at baseline (p= 0.331). At 12 months, mean BCVA was 0.14 ± 0.19 logMAR in the conventional ILM peeling group and 0.17 ± 0.18 logMAR in the inverted flap group (p= 0.08). At 12 months, 73% of eyes had a U-shape closure morphology in the conventional ILM peeling group versus 55% in the inverted flap group. At 12 months, ELM recovery rate was 96% and 86% in the conventional ILM peeling group and in the inverted flap group, respectively (p< 0.001); EZ recovery rate was 78% and 69%, respectively (p= 0.04). Conclusions: The inverted flap technique provides no advantages in terms of visual outcome and closure rate in small idiopathic macular hole surgery. Additionally, this technique seems to impair postoperative restoration of external retinal layers compared with conventional peeling.