Background: Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system caused by antibodies preferably to the optic nerve, spinal cord, and certain brain regions. Symptoms may occur at the same time or vary over a period of time. The best prognostic factor of conversion from optic neuritis to clinical definite NMO is the presence of a serum antibody to aquaporin-4 called NMO-IgG. Suspicion of NMO should be high in patients who present with simultaneous bilateral optic neuritis or recurrent attacks and in those with vision of light perception or worse or who are with acuity of 20/50 or worse after optic neuritis.