Relationship of dissociated optic nerve fiber layer appearance to internal limiting membrane peeling.

PURPOSE

The dissociated optic nerve fiber layer (DONFL) appearance features numerous arcuate striae after vitrectomy for idiopathic epiretinal membrane or macular hole. We studied the relation between the DONFL appearance and internal limiting membrane (ILM) peeling and performed static microperimetry to explore the possible mechanisms underlying the DONFL appearance.

DESIGN

Prospective cohort study.

PARTICIPANTS

Ninety-five eyes of 88 consecutive patients undergoing vitrectomy for idiopathic macular hole.

METHODS

Vitrectomy and gas tamponade were performed with or without ILM peeling. All eyes were examined postoperatively using fundus photography with blue filters. Static microperimetry was performed in 31 eyes with a clearly visible DONFL appearance.

MAIN OUTCOME MEASURE

The postoperative incidence of the DONFL appearance on blue-filtered fundus photographs. The secondary outcome measure included the microperimetry threshold value in the arcuate striae and the surrounding normal retina within the papillomacular bundle.

RESULTS

On blue-filtered photographs, 46 (62.2%) of 74 eyes with ILM peeling exhibited the DONFL appearance, compared with 0 (0%) of 21 eyes without ILM peeling (P = 0.0002). The area of the DONFL appearance was limited to the area of ILM peeling. There was no difference in the microperimetry threshold value between the arcuate striae and the surrounding normal retina (P = 0.9312).

CONCLUSION

The present study indicates that the DONFL appearance might be related to ILM peeling and is not associated with the loss of optic nerve fibers. These results are consistent with the suggestion that the DONFL appearance might be caused by cleavage of the optic nerve fiber bundles due to damage to the Müller cells, which are in close contact with the ILM and act to maintain the close proximity of the nerve fiber bundles.