Abstract
Ophthalmic and MRI evaluations of a 13-year-old boy who reported loss of visual acuity in his right eye demonstrated the presence of unilateral optic neuritis. After serological tests showed positivity for anti-aquaporin 4 antibody, he was diagnosed with neuromyelitis optica spectrum disorder. Encephalopathy and myelitis were not observed. Since his unilateral optic neuritis was considered to reflect mild disease activity, only follow-up observations were performed. Visual acuity and central scotoma improved 1 week after the first examination. In the absence of any specific treatments, good visual acuity has remained for 20 months, with no relapse of optic neuritis.