A 73-year-old woman presented with sudden-onset painless central vision loss in the left eye upon awakening. She denied scalp tenderness, jaw claudication, pain with eye movements, or dyschromatopsia. Methylprednisolone 1000mg IV was started for concern for giant cell arteritis. Neuro-ophthalmologic examination showed left relative afferent pupillary defect, decreased visual acuity (20/200 OS), and dyschromatopsia. Funduscopic examination was unrevealing for disc edema or evidence of retinal ischemia. MRI of the brain and orbits demonstrated restricted diffusion in the posterior half of the intraconal optic nerve with longitudinally extensive enhancement extending posteriorly to the optic chiasm. MRI of the cervical spine did not show any lesions. Bilateral temporal artery biopsy was negative. Inflammatory markers, MOG-IgG, Lyme, ANA, and paraneoplastic antibodies were negative. Lumbar puncture showed elevated protein and normal WBC. Serum aquaporin-4 antibodies were positive (titer 1:1000). She was diagnosed with NMOSD. Mycophenolate mofetil was initiated, as the patient refused infusion treatment. Visual acuity improved to 20/40 at follow-up. She returned nine months later with a second episode of optic neuritis in the right eye and agreed to IV treatment with inebelizumab.