NAION
Pronunciation: NAY-on
Also written as: NAION — Non-arteritic anterior ischemic optic neuropathy
Non-arteritic anterior ischemic optic neuropathy; sudden vision loss due to ischemia of the optic nerve head.
Full Definition
Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common acute optic neuropathy in patients over 50 years of age. It results from ischemia to the anterior portion of the optic nerve, typically in the setting of small optic discs and vascular risk factors such as diabetes, hypertension, and sleep apnea. The condition presents with sudden, painless vision loss, often noticed upon awakening, and is associated with optic disc swelling and altitudinal visual field defects.
Usage
Usage note: Always distinguish from AION (arteritic anterior ischemic optic neuropathy), which requires urgent treatment.
In Context
- "The patient's presentation was consistent with NAION given the altitudinal visual field defect and disc swelling." — Emergency department consultation
- "NAION typically affects patients with small, crowded optic discs and vascular comorbidities." — Medical education material