Tracking retinal nerve fiber layer loss after optic neuritis: a prospective study using optical coherence tomography.

INTRODUCTION: Optic neuritis causes retinal nerve fiber layer damage, which can be quantified with optical coherence tomography. Optical coherence tomography may be used to track nerve fiber layer changes and to establish a time-dependent relationship between retinal nerve fiber layer thickness and visual function after optic neuritis.

METHODS: This prospective case series included 78 patients with optic neuritis, who underwent optical coherence tomography and visual testing over a mean period of 28 months. The main outcome measures included comparing inter-eye differences in retinal nerve fiber layer thickness between clinically affected and non-affected eyes over time; establishing when RNFL thinning stabilized after optic neuritis; and correlating retinal nerve fiber layer thickness and visual function.

RESULTS: The earliest significant inter-eye differences manifested 2-months after optic neuritis, in the temporal retinal nerve fiber layer. Inter-eye comparisons revealed significant retinal nerve fiber layer thinning in clinically affected eyes, which persisted for greater than 24 months. Retinal nerve fiber thinning manifested within 6 months and then stabilized from 7 to 12 months after optic neuritis. Regression analyses demonstrated a threshold of nerve fiber layer thickness (75 microm), which predicted visual recovery after optic neuritis.

CONCLUSIONS: Retinal nerve fiber layer changes may be tracked and correlated with visual function within 12 months of an optic neuritis event.