Tonic pupil with giant cell arteritis.

A patient with giant cell arteritis and ischaemic optic neuropathy developed bilateral tonic pupils. This pupillary abnormality may result from ischaemia of the ciliary ganglia. Despite the propensity for patients with giant cell arteritis to develop vascular occlusions in the eye and orbit, tonic pupils have rarely been described, and several reasons for this are proposed. The arteries supplying the ciliary ganglia are frequently involved in giant cell arteritis, but their anastomotic pattern may confer protection from ischaemia. Tonic pupils may also be overlooked amidst the more dramatic manifestations of giant cell arteritis.