According to that scheme optic neuritis (ON), acute myelitis and at least two of three supportive criteria (continuous spinal cord magnetic resonance imaging (MRI) lesion encompassing over three vertebral segments, brain MRI not fulfilling diagnostic criteria for MS and aquaporin-4 immunoglobulin G (AQP4-IgG) seropositivity) should be present [3]. Here, AQP4 is linked to optic neuritis.