Anterior ischemic optic neuropathy
| Anterior ischemic optic neuropathy | |
|---|---|
| Classification and external resources | |
| Specialty | ophthalmology |
| ICD-10 | H47.0 |
| ICD-9-CM | 377.41 |
| OMIM | 258660 |
| DiseasesDB | 31309 |
| eMedicine | oph/161 |
| MeSH | D018917 |
Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision caused by damage to the optic nerve as a result of insufficient blood supply (ischemia). This form of ischemic optic neuropathy is generally divided into two types: arteritic AION (or AAION), where the loss of vision is an effect of an inflammatory disease of arteries in the head called temporal arteritis, and non-arteritic AION (abbreviated as NAION, or sometimes simply as AION) due to non-inflammatory disease of small blood vessels.
The distinction between AAION and non-arteritic AION was made to highlight the different etiologies of anterior ischemic optic neuropathy. AAION is due to temporal arteritis (also called giant cell arteritis), an inflammatory disease of medium-sized blood vessels (Chapel-Hill-Conference) that occurs especially with advancing age. In contrast, NAION results from the coincidence of cardiovascular risk factors in a patient with "crowded" optic discs. Non-arteritic AION is more common than AAION and usually occurs in a slightly younger group than AAION. While only a few cases of NAION result in near total loss of vision, most cases of AAION involve nearly complete vision loss.
Beyond this introduction, this article will focus on non-arteritic AION. For a discussion on arteritic AION see the separate article arteritic anterior ischemic optic neuropathy. Though the term "AION" can be used to describe either anterior ischemic optic neuropathy in general or non-arteritic AION specifically, in this article "NAION" henceforth will be used to refer to non-arteritic anterior ischemic optic neuropathy. Nonarteritic anterior ischemic optic neuropathy is an isolated white-matter stroke of the optic nerve (ON). NAION is the most common cause of sudden optic nerve-related vision loss, affecting more than 10,000 Americans every year, often bilaterally. No clinically effective treatments exist, largely because little is known about its pathophysiology, and there are few histopathological studies of the acute condition.
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