Arteritic ischaemic optic neuropathy (AION)

Giant cell arteritis (GCA) is the most common vasculitis in humans. It can affect arteries of all sizes, especially the temporal, vertebral and posterior ciliary arteries.

Involvement of the latter, as in AION, can cause severe and irreversible loss of vision. Occlusion of the central retinal or branch retinal arteries can also occur.

Arteries containing abundant elastic tissue are preferentially involved in GCA. For this reason, the temporal artery is highly susceptible, and intracranial arteries are usually spared. Histological examination reveals granulomatous inflammation with disruption of the internal elastic lamina. Characteristic giant cells are present in two-thirds of cases.