Non-arteritic anterior ischemic optic neuropathy (NAION) is a form of ischemic optic neuropathy.
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Epidemiology
It is considered the most common acute optic neuropathy in patients over 50 years of age.
Risk factors
medications (e.g. sildenafil, amiodarone)
Clinical presentation
The presentation is with acute, monocular, visual loss 4. The visual loss typically consists of an altitudinal field loss, usually inferiorly, and classically presents upon waking 4,5. Although usually painless, pain may be present in a minority (up to 12%) of patients 4.
On examination, there is ipsilateral optic disc swelling which later progresses to atrophy and pallor 4. In cases of sequential NAION, pseudo-Foster Kennedy syndrome may be present 4.
Pathology
The condition is thought to be caused by infarction of the laminar or retrolaminar portions of the optic nerve head supplied by the short posterior ciliary arteries (SPCAs), possibly due to relative nocturnal hypotension 4.
Treatment and prognosis
No disease-modifying treatment exists 4. Significant recovery of visual acuity occurs in approximately 40% of patients 4.
Differential diagnosis
other causes of optic neuropathy
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