Dissociated optic nerve fiber layer appearance after internal limiting membrane peeling for idiopathic macular holes

Abstract

Purpose: To investigate the characteristics and incidence of a dissociated optic nerve fiber layer (DONFL) appearance in eyes after idiopathic macular hole surgery.

Design: Retrospective, nonrandomized, comparative interventional case series.

Participants: Ninety-one eyes with idiopathic macular holes that were closed after 1 pars plana vitrectomy were studied. Among these, 67 eyes had the internal limiting membrane (ILM) peeled (ILM-peeled), and 24 did not have the ILM peeled (ILM-unpeeled).

Methods: All patients received a complete ophthalmologic examination and color fundus photography preoperatively and postoperatively. Twenty ILM-peeled eyes and 9 ILM-unpeeled eyes were also examined by optical coherence tomography (OCT3), microperimetry by scanning laser ophthalmoscope (SLO), and macular sensitivity measurements by Humphrey visual field testing more than 4 months after the vitrectomy.

Main outcome measures: Development of a DONFL on fundus photographs and OCT3, and the functional evaluation of a DONFL by best-corrected visual acuity, SLO-microperimetry, and Humphrey visual field testing.

Results: In 67 ILM-peeled eyes, a DONFL appearance was found in 36 eyes (54%) in color fundus photographs. A DONFL appearance was not detected in any of the 24 ILM-unpeeled eyes. Focal dehiscence of the optic nerve fiber layer was found in all 20 examined eyes by OCT3. No scotoma was found corresponding to the DONFL by SLO microperimetry. The best-corrected visual acuity and macular sensitivity were not significantly different in eyes with and without a DONFL appearance (P>0.05). A DONFL appearance was not detected in all 20 eyes examined within 1 month after surgery, was detected in all 16 eyes examined between 1 and 3 months, and no new cases were detected after 3 months. The DONFL appearance became more distinct until about 6 months after first detection and seemed not to change subsequently.

Conclusions: The DONFL appearance in about half of the eyes with ILM peeling and none in eyes without ILM peeling strongly suggest that the DONFL appearance is related to ILM peeling. The OCT findings in eyes with no functional abnormality by SLO microperimetry suggested that the DONFL is due to a dehiscence of the optic nerve fiber layer and not a true nerve fiber layer defect.