Optic Neuritis Leading to Vision Loss: A Case of MOG-Associated Disease with Successful Immunotherapy

BACKGROUND Myelin oligodendrocyte glycoprotein (MOG)-associated disease (MOGAD) is a recently described inflammatory demyelinating disease of the central nervous system (CNS), which needs to be distinguished from aquaporin-4 (AQP4)-IgG-positive neuromyelitis optica spectrum disorder (AQP4-IgG+NMOSD) and multiple sclerosis (MS). CASE REPORT A 42-year-old woman presenting with loss of vision due to optic neuritis was admitted to the Naval Medical Center in October 2022. She had optic disc edema, blurred visual margins, optic disc pallor, and deficient visual field in both eyes. Cranial magnetic resonance imaging (MRI) showed bilateral optic nerve thickening, tortuosity, and swelling, especially on the right side. Orbital MRI T2 sequence showed the typical "double track sign" change. The titers of MOG-IgG in CSF and serum were 1: 1 (+) and 1: 32 (+) separately, so MOGAD was diagnosed. The primary treatment was intravenous methylprednisolone for 2 weeks, after which the blurred vision improved and MRI showed the optic nerve lesions disappeared. She was discharged and oral corticosteroids were tapered gradually, and 1 month later, the symptom had vanished without recurrence, cranial MRI was normal, and MOG-IgG in CSF and serum were negative. Low-dose oral corticosteroids were continued for 6 months, with no relapse and normal cranial MRI, so we stopped corticosteroid therapy. At 1-year follow-up, the symptoms had not recurred. CONCLUSIONS A 42-year-old woman presented with loss of vision due to optic neuritis and positive antibody testing for MOG. MOGAD was diagnosed, and timely immunotherapy was effective.