Purpose: The purpose of this study is to differentiate neuromyelitis optica and its related disorders. Materials and Method: A retrospective single site study of 104 patients from July 2014 to October 2017 with optic neuritis and/or myelitis was done. After history taking and complete ocular examination, neurological examination, cerebrospinal fluid examination, magnetic resonance imaging and aquaporin 4 antibody testing, patients were categorised as neuromyelitis optica, multiple sclerosis and

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... tiple sclerosis and others. Results: Neuromyelitis optica was diagnosed in 38 patients, multiple sclerosis in 48 patients and 18 were others. Female predominance (76%) was noted in neuromyelitis optica patients. Seropositivity for aquaporin 4 autoantibodies was associated with higher relapse rate. In neuromyelitis optica 55% patients responded to steroid therapy, 30% referred for plasmapheresis, and 15% patients needed imunosuppressive therapy. Conclusion: Considerable overlap exists between neuromyelitis optica and multiple sclerosis, both have to be differentiated because both diseases have different treatment guidelines.