Ischemic optic neuropathy is a common cause of sudden visual loss in patients over 50 years of age. The most common form of this condition, called nonarteritic anterior ischemic optic neuropathy, occurs in the context of “vasculopathic” risk factors, particularly diabetes, hypertension, or hyperlipidemia. Less commonly, nonarteritic ischemic optic neuropathy may be posterior (ie, affecting the optic nerve behind the eyeball). Rare causes of nonarteritic ischemic optic neuropathy include associations with surgery (cataract surgery, spinal surgery, cardiac, and transplant surgeries), sleep apnea, and amiodarone and phosphodiesterase inhibitors. Giant cell arteritis is typically the cause of arteritic ischemic optic neuropathy, and is a true visual emergency because the second eye may become involved within days if giant cell arteritis is not treated promptly. Arteritic ischemic optic neuropathy can affect the anterior or posterior optic nerve.
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• Ischemic optic neuropathy is named according to cause (nonarteritic or arteritic) and location (anterior with optic disc swelling or posterior with an initially normal appearing optic disc).
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• Nonarteritic anterior ischemic optic neuropathy is a common cause of vision loss in individuals over 50 years of age and does not have a proven treatment.
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• Nonarteritic anterior ischemic optic neuropathy is associated with vasculopathic risk factors, some medications, obstructive sleep apnea, and crowded optic nerve heads.
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• Nonarteritic posterior ischemic optic neuropathy is rare.
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• Arteritic anterior or posterior ischemic optic neuropathy is typically caused by giant cell arteritis, which requires emergent treatment to prevent other ischemic events.
Historical note and terminology
In 1966 Miller and Smith described a syndrome of acute, monocular, painless visual loss, afferent pupillary defect, and optic disc edema, terming it, ischemic optic neuropathy (47). The term ischemic optic neuropathy identified the non-inflammatory nature of the disorder, which previously had been variously named “vascular pseudopapillitis,” “arteriosclerotic papillitis,” and “ischemic papillitis.” Hayreh subsequently added the keyword “anterior,” to denote those cases of ischemic optic neuropathy that included optic disc edema in the acute phase (non-arteritic anterior ischemic optic neuropathy), differentiating them from the rarer posterior ischemic optic neuropathy, in which the optic disc appearance is initially normal (25). The term arteritic ischemic optic neuropathy is used to describe ischemic optic neuropathy that occurs in the setting of vascular inflammation, typically giant cell arteritis.