Previous studies primarily compared retinal structure and function between NMOSD and either multiple sclerosis patients or controls based on clinical diagnostic criteria.[12–22] It has been found that 60%−80% of patients with definite NMO but only 5%−25% of patients with recurrent isolated ON were seropositive.[8] Therefore, the pathological significance of AQP4 Ab or AQP4 Ab-positive serum on retinal structural and functional outcomes is still unclear. The gene discussed is AQP4; the disease is neuromyelitis optica.