14 cases of posterior ischemic optic neuropathy (PION) were clinically analyzed, in whom we excluded known etiologies of optic nerve disturbances and confirmed the decreased blood supply to the posterior portion of the optic nerve. On the basis of our clinical findings, we have proposed the following criteria for the diagnosis of idiopathic PION: (1) sudden onset of unilateral visual disturbance in older patients; (2) normal optic disc, subsequently developing simple optic atrophy; (3) hypertensive and arteriosclerotic changes in the retinal vessels; (4) varying degrees of impaired vision, variable visual field defects; (5) associated systemic disease such as hypertension, diabetes mellitus, hyperlipemia, hypotension, etc.; (6) exclusion of other demonstrable causes of optic nerve disturbances, and (7) confirmation of abnormal hemodynamics in the posterior portion of the optic nerve by carotid angiography, ophthalmodynamography, ophthalmodynamometry and fluorescein fundus angiography.