AAION

Acute Anterior Ischemic Optic Neuropathy (AAION) is a sudden, painless loss of vision due to ischemia of the optic nerve head. It most often affects people over 60. The term AAION is usually used for the arteritic form, contrasted with non-arteritic AION (NAION).

Etiology and pathophysiology: The arteritic form results from inflammatory vasculopathy of the short posterior ciliary arteries, most often due to giant cell arteritis. Ischemia of the optic nerve head causes edema in the acute phase, followed by pallor and atrophy. NAION, by contrast, arises from small-vessel disease and vascular risk factors.

Clinical features: Sudden, unilateral, painless vision loss with an afferent pupillary defect. Systemic symptoms of GCA may accompany arteritic AAION (headache, jaw claudication, scalp tenderness). Fundoscopy typically shows optic disc edema; later stages reveal pallor and atrophy.

Diagnosis: Obtain ESR and CRP; temporal artery biopsy can confirm GCA. Prompt ophthalmic examination distinguishes AAION from NAION by disc edema and systemic signs. Imaging and laboratory studies may be used to assess vascular involvement and rule out other causes.

Treatment: In suspected AAION due to GCA, initiate high-dose corticosteroids promptly to reduce the risk of involvement in the fellow eye and systemic complications, even before biopsy results. Follow with rheumatology management and tapering; address cardiovascular risk factors.

Prognosis and epidemiology: AAION occurs mainly in older adults and carries a high risk of severe, sometimes irreversible vision loss if not treated quickly. The prognosis depends on timely treatment and underlying disease control; fellow-eye involvement remains a concern without systemic therapy.