We aimed to assess the efficacy of biologic therapy in refractory non-Multiple Sclerosis (MS) Optic Neuritis (ON), a condition more infrequent, chronic and severe than MS ON. This was an open-label multicenter study of patients with non-MS ON refractory to systemic corticosteroids and at least one conventional immunosuppressive drug. The main outcomes were Best Corrected Visual Acuity (BCVA) and both Macular Thickness (MT) and Retinal Nerve Fiber Layer (RNFL) using Optical Coherence Tomography (OCT). These outcome variables were assessed at baseline, 1 week, and 1, 3, 6 and 12 months after biologic therapy initiation. Remission was defined as the absence of ON symptoms and signs that lasted longer than 24 h, with or without an associated new lesion on magnetic resonance imaging with gadolinium contrast agents for at least 3 months. We studied 19 patients (11 women/8 men; mean age, 34.8 ± 13.9 years). The underlying diseases were Bechet's disease (