Posterior ischemic optic neuropathy.

3 patients (5 eyes) with posterior ischemic optic neuropathy (PION) are presented. PION is a distinct clinical entity, caused by ischemia of the posterior part of the optic nerve. These eyes presented with a visual acuity varying from normal to no light perception, optic nerve-related visual field defects, and no fundus abnormality (on ophthalmoscopy or fluorescein fundus angiography) at the onset of the disease and for about a month thereafter, but after about 5-6 weeks the optic disc developed atrophic changes. The pathogenesis, differential diagnosis and possible management of PION are discussed.