A visual impairment occurs in about 50% of patients with giant cell arteritis (GCA), an amaurosis fugax (AF) in about 30%, and diplopia in about 10%. An arteritic anterior ischemic optic neuropathy was found in about 80%-90% of patients with visual loss and an arteritic central retinal artery occlusion in about 10%-20%. Without therapy, involvement of the fellow eye may occur within hours or days in a patient with unilateral blindness. Involvement of the anterior segment of the eye (iris ischemia, episcleritis) is rare. Ocular ischemic syndrome is defined by visual loss with hypotony, ischemia of the iris, and cotton wool spots (CWS). CWS may already occur with AF episodes. In the case of strong suspicion of GCA, immediate therapy with steroids is indicated. Duplex sonography and a gadolinium MRI examination are of diagnostic importance. A biopsy of the temporal artery may be carried out after the initiation of therapy.