Late-Onset Neuromyelitis Optica Spectrum Disorder Mimicking a Non-Arteritic Anterior Ischemic Optic Neuropathy-Case Report.

A 60-year-old white woman presented to the emergency department with painless decrease of visual acuity in the left eye (LE). The diagnosis of a non-arteritic anterior ischemic optic neuropathy in the LE was established based on the clinical picture and the results of static perimetry, fluorescein angiography, visual evoked potential, and magnetic resonance imaging (MRI) of the brain and orbit. Six months later, the patient reported visual impairment in the right eye (RE). Best corrected visual acuity (BCVA) in the RE was 5/10. Gadolinium-enhanced MRI showing inflammation of both optic nerves and the optic chiasm in correlation with positivity for immunglobulin G antibody against aquaporin-4 led to the diagnosis of late-onset neuromyelitis optica spectrum disorder. High-dose intravenous methylprednisolone therapy followed by oral tapering was administered and oral azathioprine was started to reduce the risk of further relapse. At discharge, BCVA was 5/5 in the RE. The patient remains under the care of neurology and ophthalmology clinics, with no recurrences for two years. The possibility of neuromyelitis optica spectrum disorder with optic neuritis in older patients is important in the differential diagnosis of ischemic optic neuropathy.