Correct. Giant cell arteritis is an autoimmune inflammation of medium-sized arteries, especially branches of the external carotid artery. Patients may report headache, scalp tenderness, and jaw claudication. If not treated, patients may develop sudden loss of vision in one eye. The unaffected eye is often affected soon afterwards. Examination will reveal an afferent pupillary defect and a swollen optic disc, as seen here. Patients require immediate intravenous corticosteroid treatment and a temporal artery biopsy.