Recovery from optic neuritis attack in neuromyelitis optica spectrum disorder and multiple sclerosis

Background Both neuromyelitis optica spectrum disorder (NMOsd) and multiple sclerosis (MS) patients experience optic neuritis (ON) attacks characterized by rapidly reduced best-correct visual acuity (BCVA) and slow recovery. Prognosis and effects of recurrence on recovery may differ between disorders but remain unclear. Objective To compare ON severity, time and degree of recovery and effects of previous ON between NMOsd and MS patients. Methods Retrospective chart review was performed. BCVA measurements acquired before ON, at nadir and during recovery were retrospectively reviewed. Records were obtained on 69 ON attacks in 36 NMOsd patients and 43 attacks in 28 MS patients, including first episodes and recurrences. Results NMOsd patients exhibited significantly lower BCVA values at all time points after attack (P < 0.05), reached nadir earlier (P = 0.014) and regained a smaller fraction of baseline BCVA than MS patients (P < 0.001). In NMOsd, relapsed ON resulted in worse recovery and tended to reach nadir earlier than first-episode ON (P = 0.030 and 0.059, respectively). In MS, relapsed ON also reached nadir earlier (P = 0.042); however, there was no difference in recovery. Conclusions Recovery from ON was poorer in NMOsd than in MS and was negatively affected by previous ON attacks.