Time to steroid treatment in severe acute optic neuritis

OBJECTIVES: Steroid treatment can accelerate visual recovery in patients with optic neuritis (ON), but it is unknown whether the timing of the start of treatment influences the outcome. The main purpose of this observational study was to assess the effect of early onset steroid treatment of ON on visual prognosis and retinal morphology. METHODS: Forty‐nine patients with acute mild/moderate (n = 21) or severe (n = 28) ON, and an equal number of healthy controls were enrolled. Patients with severe ON either received early onset steroid treatment (initiated within 1 week of presentation with visual loss) (n = 9), late‐onset treatment (initiated after 1 week) (n = 13), or no treatment (n = 6). Visual function and retinal morphology was studied after 6 and 12 months. RESULTS: All measures of visual function had improved after 6 months (p ≤ 0.03) in the three groups with severe ON. This was not the case for Rayleigh match setting range (SR) in the nontreated group (p = 0.24), or for SR (p = 0.08) and latency to P100 of visual evoked potential (p = 0.08) in the late‐onset treated group. After 12 months, further improvement occurred in the nontreated and late‐treated groups, but not in the early treated group. Macular retinal nerve fiber layer (mRNFL) and ganglion cell plus inner plexiform layer had decreased significantly (p ≤ 0.001) in all three groups with severe ON after 6 months. After 12 months, only mRNFL had further significantly decreased and only in the late‐onset treated group (p = 0.02). CONCLUSION: The beneficial effects of early onset steroid treatment of ON is limited to a few months whereas the long‐term prognosis is independent of the timing of treatment.