This document summarizes different types of ischemic optic neuropathies. It describes non-arteritic anterior ischemic optic neuropathy (NAAION) as being caused by occlusion of the short posterior ciliary arteries, often affecting older patients with structural crowding at the optic nerve head. Treatment focuses on underlying risk factors but does not restore vision. Arteritic anterior ischemic optic neuropathy (AAION) is caused by giant cell arteritis which involves large arteries and risks blindness if not treated immediately with high-dose steroids. Posterior ischemic optic neuropathy (PION) is rare and caused by ischemia of the retrolaminar optic nerve.