Joseph F.Rizzo

　　Massachusetts Eye and Ear Infirmary/Harvard Medical School

　　Ischemic Optic Neuropathy(ION)is the most common form of non-glaucomatous optic neuropathy in older adults.ION occurs either in as an“anterior”or“posterior”form，although the latter is quite uncommon.This presentation will review the two most common forms of anterior ION——non-arteritic anterior ischemic optic neuropathy(NAION)and arteritic ION.For each，the presumed mechanisms underlying the damage to the optic nerve will be reviewed，and the typical clinical presentations will be discussed.The challenge in distinguishing NAION from another common form of non-glaucomatous optic neuropathy–optic neuritis–will be emphasized.NAION cannot be treated，although the use of neuroprotective drugs to reduce the damage to the optic nerve is being widely investigated.A more substantial discussion will be presented on the subject of giant cell arteritis(GCA)，which is the cause of almost all cases of arteritic ION.The approach to management and treatment of GCA will be reviewed in detail.