Dissociated optic nerve fiber layer (DONFL)
Dissociated Optic Nerve Fiber Layer Appearance After Macular Hole Surgery: A Randomized Controlled Trial Comparing The Temporal Inverted Internal Limiting Membrane Flap Technique Versus Conventional Peeling
Alix Ehrhardt , Marion Delpuech , Amandine Luc , Astrid Zessler , Geoffrey Pastor , Karine Angioi-Duprez , Jean-Paul Berrod , Nathalie Thilly , Jean-Baptiste Conart
Purpose: To evaluate the effect of the temporal inverted internal limiting membrane (ILM) flap technique compared to conventional ILM peeling on the extent of dissociated optic nerve fiber layer (DONFL) and the retinal sensitivity in patients undergoing macular hole (MH) surgery.
Design: Single-center, prospective, open-label randomized controlled clinical trial PARTICIPANTS: Patients requiring vitrectomy for MH > 250 μm METHODS: Patients were randomly assigned (1/1) to one of the two groups: the control group undergoing standard ILM peeling and the experimental group (flap group) undergoing the temporal inverted ILM flap technique.
Main outcome measures: The primary outcome measure was the total DONFL score at 3 months after surgery. Important secondary outcomes were microperimetry results, primary MH closure rate, rates of external limiting membrane (ELM) and ellipsoid zone (EZ) recovery and best-corrected visual acuity (BCVA).
Results: Sixty-five patients were recruited between February 2018 and July 2020; 60 patients had primary outcome data. 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 postoperatively (p=0.145).
The focal depressions characteristics of DONFL were limited to the temporal side of the fovea in the flap group, while they were found all around the fovea in the control group on SD-OCT images. The MH closure rate, EZ and ELM recovery rates, and BCVA were similar between the 2 groups (p=1, p=0.252 and p=0.450, respectively).
The 3-month overall median retinal sensitivity (MRS) and MRS improvement in the control group were comparable to those observed in the flap group (p=0.142 and p=0.916, respectively). There was also no significant difference between the 2 techniques when considering the temporal area (p=0.105) or the nasal area (p=0.468).
Conclusion: The temporal inverted ILM flap technique reduced the extent of DONFL by preserving the nasal part of the fovea. However, the overall DONFL score was similar between the 2 techniques. In addition, median retinal sensitivity and BCVA did not differ from that obtained after complete ILM peeling.