AQP4 and neuromyelitis optica: Although vascular abnormalities including retinal artery attenuation have been reported in eyes with NMO,[41] leakage from the retinal vessels has not been demonstrated.[41] The blood-brain barrier has been reported to be compromised in eyes with NMOSD,[42] and we suggest that the blood-retinal barrier might also be compromised giving access of anti-AQP4 antibody to the retinal tissues.