Neuromyelitis Optica Spectrum Disorder (NMOSD) (Neuromyelitis Optica; Devic Disease) By Michael C Levin, MD, College of Medicine, University of Saskatchewan Reviewed / Revised May 2023 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points Neuromyelitis optica spectrum disorder is a demyelinating disorder that predominantly affects the eyes and spinal cord but can affect other structures in the central nervous system (CNS) that contain aquaporin 4.