Dynamics of retinal injury after acute optic neuritis.

OBJECTIVE We set out to assess the dynamics of retinal injury after acute optic neuritis (ON) and their association with clinical visual outcomes. METHODS Thirty-one consecutive patients with acute ON were prospectively analyzed over a 6-month follow-up period. Each month, we used optical coherence tomography (OCT) to assess the thickness of peripapillary retinal nerve fiber layer (pRNFL) and segmented macular layers, as well as high-contrast visual acuity, low-contrast visual acuity (LCVA), color visual acuity (CVA), and visual fields (VF). RESULTS In this prospective study, we found that 6 months after clinical onset, ON eyes suffered a reduction in pRNFL (-45.3 μm) and macular thickness (-17.3 μm). Macular atrophy was due to the decrease of macular RNFL thickness (-7.8 μm) and that of the ganglion cell layer and inner plexiform layer (GCIP, -11.3 μm), whereas the thickness of the outer retinal layers increased slightly. The macular RNFL and GCIP thickness decreased in parallel, yet it always occurred more rapidly and more severely for the GCIP. The change in the GCIP thickness in the first month predicted the visual impairment by month 6; a decrease ≥ of 4.5 μm predicted poor LCVA (sensitivity of 93% and specificity of 88%), and a decrease of ≥ 7 μm predicted poor VF and CVA (sensitivity of 78% and 100% and specificity of 63% and 66%, respectively). INTERPRETATION Retinal axonal and neuronal damage develops quickly after ON onset. Assessment of ganglion cell layer thickness by OCT after ON onset can be used as an imaging marker of persistent visual disability.