Assessment of Clemastine Fumarate as a Remyelinating Agent in Acute Optic Neuritis (ReCOVER)

Inclusion Criteria: * Patients diagnosed or suspected to have an acute demyelinating optic neuritis in at least one eye within 3 weeks from the onset of any visual symptom other than pain * Use of disease-modifying therapies is not a contraindication * Use of appropriate contraception during the period of trial (women) * Understand and sign the informed consent Exclusion Criteria: * Other major ophthalmologic diseases / concomitant ophthalmologic disorders (e.g. diabetes, macular degeneration, glaucoma, severe myopia, etc) * Disc hemorrhages in the qualifying eye * No light perception in qualifying eye * Simultaneous bilateral optic neuritis * Cotton wool spots in the qualifying eye * Macular star in the qualifying eye * History of significant cardiac conduction block * History of cancer * Suicidal ideation or behavior in 6 months prior to baseline * Pregnancy, breastfeeding or planning to become pregnant * Involved with other study protocols simultaneously without prior approval * Concomitant use of any other putative remyelinating therapy as determined by the investigator * Serum creatinine \> 1.5 mg/dL; aspartate transaminase (AST), alanine transaminase (ALT), or alkaline phosphatase \> 2 times the upper limit of normal * History of drug or alcohol abuse within the past year * Untreated B12 deficiency (as determined by B12 serological assessments and metabolites including methylmalonic acid (MMA) and homocysteine) or untreated hypothyroidism * Clinically significant car…