Should Aquaporin-4 Antibody Test Be Performed in all Patients With Isolated Optic Neuritis?

Background: Optic neuritis (ON) may be the initial manifestation of neuromyelitis optica spectrum disorder (NMOSD). Aquaporin-4 antibody (AQP4 Ab) is used to diagnose NMOSD. This has implications on prognosis and is important for optimal management.