Ocular ischaemic syndrome due to giant cell arteritis.

Giant cell arteritis (GCA) is a large vessel vasculitis with devastating visual consequences if left untreated. Classically, GCA has a predilection for the short posterior ciliary arteries which supply the optic nerve head, causing sudden painless visual loss with the development of arteritic anterior ischaemic optic neuropathy (AAION). Other ocular manifestations of GCA include central retinal artery occlusion, oculomotor nerve palsy, posterior ischaemic optic neuropathy and ocular ischaemic syndrome (OIS). OIS is a rare clinical entity, typically stemming from severe, unilateral carotid artery disease. It may present with anterior segment ischaemia heralded by hypotony and corneal oedema. Rarely, it may occur in cases of GCA. We describe an atypical presentation of OIS and oculomotor nerve palsy with contralateral AAION in an elderly patient with a delayed diagnosis of biopsy-proven GCA. This case exemplifies the importance of suspicion, early diagnosis and initiation of treatment in GCA to prevent irreversible loss of vision.