Dissociated Optic Nerve Fiber Layer Appearance after Macular Hole Surgery: A Randomized Controlled Trial Comparing the Temporal Inverted Internal Limiting Membrane Flap Technique with Conventional Peeling

Abstract

To evaluate the effect of the temporal inverted internal limiting membrane (ILM) flap technique compared with that of conventional ILM peeling on the extent of the dissociated optic nerve fiber layer (DONFL) and retinal sensitivity in patients undergoing macular hole (MH) surgery. Single-center, prospective, open-label, randomized controlled clinical trial. Patients requiring vitrectomy for MHs sized > 250 μm. Patients were randomly assigned (1:1) to 1 of the following 2 groups: (1) the control group undergoing standard ILM peeling and (2) the experimental group (flap group) undergoing the temporal inverted ILM flap technique. The primary outcome measure was the total DONFL score at 3 months after surgery. Important secondary outcomes were microperimetry results, primary MH closure rate, external limiting membrane (ELM) and ellipsoid zone (EZ) recovery rates, and best-corrected visual acuity (BCVA). Sixty-five patients were recruited between February 2018 and July 2020; primary outcome data were available for 60 patients. The median DONFL score was 7.0 (3.0-12.5) in the control group and 5.0 (1.5-8.5) in the flap group at 3 months after surgery (P= 0.145). The focal depressions characteristic of the DONFL were limited to the temporal side of the fovea in the flap group, whereas they were found all around the fovea in the control group on spectral-domain OCT images. The MH closure rate (P= 1), EZ and ELM recovery rates (P= 0.252), and BCVA (P= 0.450) were similar between the 2 groups. The 3-month overall median retinal sensitivity (MRS) (P= 0.142) and MRS improvement (P= 0.916) in the control group were comparable with those observed in the flap group. In addition, there was no significant difference between the 2 techniques when considering the temporal area (P= 0.105) or the nasal area (P= 0.468). The temporal inverted ILM flap technique reduced the extent of the DONFL by preserving the nasal part of the fovea. However, the overall DONFL score was similar between the 2 techniques. In addition, the MRS and BCVA did not differ from those obtained after complete ILM peeling.