Ischemic optic neuropathy and giant cell arteritis.

Acute loss of vision due to anterior ischemic optic neuropathy, both arteritic and nonarteritic, demands investigation and where indicated, treatment as an emergency. While advances continue in the understanding of the pathophysiology and investigation of arteritic anterior ischemic optic neuropathy, the nonarteritic form presents a major therapeutic problem, particularly in the absence of a satisfactory clinical technique for the measurement of optic nerve head blood flow. Because of steroid resistance and side effects of chronic steroid therapy in giant cell arteritis, alternative immunosuppressive agents are being explored. In nonarteritic ischemic optic neuropathy, etiologic factors such as activated protein C resistance raise the possibility of evaluation for prothrombotic states, while calcium channel blockers offer prospects for the relief of ischemic effects at the cellular level.