AQP4 and neuromyelitis optica: Indeed, in several studies, the proportion of seropositive patients with NMOSD was not described, [13,18–20,29] while in others [12,14,16,22,25,28] clinical parameters were not compared between AQP4 Ab-positive and -negative eyes within the NMOSD group (comprising 52% to 100% of AQP4 Ab-positive NMO patients in these studies).