Anterior Ischemic Optic Neuropathy (NAION)

BASICS


DESCRIPTION


Sudden, painless, unilateral visual loss, associated with swelling of the optic disc secondary to vascular insufficiency.


EPIDEMIOLOGY


Incidence


2–10 individuals per 100,000 over 50 years old


Prevalence


1,500–6,000 new cases per year in the US.


RISK FACTORS


• Small vessel disease (1)[B]


• Hypertension


• Diabetes


– Hypercholesterolemia


– Migraine


– Sleep apnea


– Hypoperfusion


– Amiodarone


– Erectile dysfunction medication (unproven)


Genetics


None recognized.


GENERAL PREVENTION


Recommended: Patients who have suffered NAION in one eye should control risk factors and be cautioned in regard to potential nocturnal or anesthesia related hypotension/hypo-perfusion.


PATHOPHYSIOLOGY


Ischemia secondary to vascular insufficiency related to small vessel perfusion at the optic nerve head. (Indirect evidence, no causative factor in a pathologic specimen identified to date).


ETIOLOGY


Anatomic theory: Condition noted to be associated with small, crowded optic disc with small cup to disc ration in fellow eye (so called disc at risk).


COMMONLY ASSOCIATED CONDITIONS


• Diabetes


• Hypertension


• Migraine


DIAGNOSIS


HISTORY


• Sudden, painless, unilateral vision loss


• Often noted upon awakening


PHYSICAL EXAM


• Decreased visual acuity


• Reduced color vision


• Sluggish pupil with afferent pupillary defect


• Visual field deficit (altitudinal)


• Optic disc edema, segmental with peri-papillary intra-retinal hemorrhage


• Crowded optic disc in fellow eye with small cup to disc ratio, (disc at risk)



ALERT


Must distinguish from arteritic form of ischemic optic neuropathy secondary to giant cell arteritis, because if left untreated, there is a 70% incidence of the second eye being involved within 10–14 days, resulting in bilateral visual loss.

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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Anterior Ischemic Optic Neuropathy (NAION)
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