anterior ischaemic optic neuropathy
neuropathy, anterior ischaemic optic (AION)
A group of disorders that have in common ischaemia of the anterior portion of the optic nerve (especially the optic nerve head). Affected patients, usually between 50 and 75 years of age, present with sudden, severe visual loss often accompanied by periocular pain and jaw claudication. The disc is pale and swollen and severe optic atrophy eventually ensues. Ischaemia is due either to inflammation of the arterioles (posterior ciliary arteries) supplying blood to the anterior portion of the optic nerve (i.e. arteritic) or to an idiopathic aetiology (i.e. non-arteritic). Arteritic AION generally affects older individuals and is most commonly associated with temporal (giant cell) arteritis. Systemic findings include weight loss, malaise, scalp and joint pain and tenderness, and possibly hypertension. Rapid diagnosis and treatment (usually corticosteroids) is crucial in order to avoid permanent visual loss as well as systemic complications. Non-arteritic AION generally affects younger patients and causes severe visual loss. There are few systemic effects of the condition. No specific treatment has been identified. See arteriosclerosis; altitudinal hemianopia.