Neuromyelitis optica (NMO), also known as Devic's syndrome, is a rare autoimmune demyelinating disease that occurs in the central nervous system, characterized by recurrent inflammation of the optic nerve and spinal cord, often leading to blindness or limb disability, and a poor prognosis. NMO-IgG (also known as AQP4 antibody) is a specific protein expressed in NMO patients and can be used as a reference for clinical diagnosis.