MOG-IgG-Positive Optic Neuritis in an Adolescent Female: A Case Report of Excellent Visual Recovery Following Corticosteroid Therapy

Background: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an inflammatory demyelinating disorder of the central nervous system that can present with optic neuritis, particularly in children and young adults. MOG-IgG-associated optic neuritis may cause severe visual loss and optic disc swelling, but visual recovery after corticosteroid treatment can be substantial. Case presentation: A 16-year-old female presented with acute-onset visual loss in the left eye. Best-corrected visual acuity was 6/6 in the right eye and 4/60 in the left eye. A relative afferent pupillary defect and reduced colour vision were present in the affected eye, and fundus examination showed optic disc oedema. Visual-field testing demonstrated generalised depression in the left eye. Brain MRI and Orbit was reported as normal. Aquaporin-4 IgG (AQP4-IgG) was negative, while MOG-IgG was positive. The patient received intravenous methylprednisolone 1 g daily for five days, followed by oral corticosteroids at 1 mg/kg/day. Two weeks after treatment initiation, visual acuity in the left eye had improved to 6/6, with reduced disc oedema and improvement in the visual-field abnormalities. Conclusion: MOGAD should be considered in adolescents presenting with acute optic neuritis, particularly when severe visual loss and optic disc oedema are present. A normal brain and orbit MRI and does not exclude MOGAD. Early treatment and follow-up are important because the disease may relapse.