Inverted internal limiting membrane flap technique versus complete internal limiting membrane peeling in large macular hole surgery: a comparative study

BackgroundTo compare the anatomical and functional outcomes of the inverted internal limiting membrane (ILM) flap technique and the complete ILM removal in the treatment of large stage 4 macular hole (MH)>400 mu m and to evaluate reconstructive anatomical changes in foveal microstructure using spectral-domain optical coherence tomography.MethodsThis is a retrospective, consecutive, nonrandomized comparative study of patients affected by idiopathic, myopic or traumatic stage 4 MH (minimum diameter>400 mu m) treated with 25-gauge pars-plana vitrectomy with either complete ILM peeling (n=23, Group 1) or inverted ILM flap technique (n=23, Group 2), between August 2016 and August 2018. Main outcomes measured were the MH closure rate assessed by spectral-domain optical coherence tomography and the best-corrected visual acuity (BCVA) at six months. Foveal microstructure reconstructive changes were evaluated using SD-OCT to determine predictive factors of postoperative BCVA.ResultsClosure of MH was achieved in 16/23 cases of Group 1 (70%) and in 22/23 cases of the Group 2 (96%). Surgical failure was reported in 6 cases of Group 1 and 1 case of Group 2. The MH closure rate was significantly higher with the inverted ILM flap technique (P-value=0.02). Average BCVA (LogMAR) changed from 1.040.32 to 0.70 +/- 0.31 in Group 1 and from 0.98 +/- 0.22 to 0.45 +/- 0.25 in Group 2 (P-value=0.005) at 6months. Improvement in BCVA (>0.3 LogMAR units) was statistically higher in the Group 2 (P-value=0.03). Restoration of foveal microstructure was significantly higher in the Group 2 at 6months (52% vs 9%, P-value <0.01). In Group 2, the integrity of the external limiting membrane at 3months postoperatively was the only significant feature correlated with postoperative BCVA at 6months (r=0.562; P-Value=0.01, forward stepwise regression analysis).Conclusion Inverted ILM flap technique is more effective than the classic ILM peeling for the closure of large stage 4 MHs>400 mu m, improving both anatomical and functional outcomes. Early recovery of the external limiting membrane at 3months is a positive predictive value of postoperative BCVA 6months after inverted ILM flap technique.