Optic neuropathy Nonarteritic anterior ischemic optic neuropathy Nonarteritic anterior ischemic optic neuropathy is caused by infarction of the laminar or retrolaminar portion of the optic nerve head supplied by the short posterior ciliary arteries. Clinically NAION is characterized by sudden, usually painless, loss of vision in one or both eyes. Examination findings include decreased visual acuity, a visual field defect, decreased color vision, a relative afferent pupillary defect, and optic disc swelling. HP:0007634 An acute condition characterized by sudden visual loss (usually discovered in the morning), optic disc edema at onset, optic disc-related visual field defects. Nonarteritic anterior ischemic optic neuropathy can be associated with flame hemorrhages on the swollen disk or nearby neuroretinal layer, and sometimes with nearby cotton-wool exudates. UMLS:C1852242 Nonarteritic anterior ischaemic optic neuropathy