Giant cell arteritis and blindness.

The etiology of giant cell arteritis (temporal arteritis, cranial arteritis) is still obscure. Polymyalgia rheumatica is probably a stage of the same disease. It causes systemic and localized symptoms, usually in patients older than 55 years, and is not uncommon as a cause of loss of vision. The sedimentation rate is unusually high. The diagnosis is defintively established by biopsy. The response to steroid therapy is dramatic.