Etiology Tobacco and alcohol addiction, drug intoxication, nutritional and metabolic disorders, multiple sclerosis, systemic infectious diseases, intraocular diseases, trauma, and tumors. Clinical manifestations 1. manifestations and signs of anterior segment ischemic optic neuropathy sudden decrease in visual acuity, typical visual field defects; headache, eye pain, especially due to temporal arteritis; gray-white edema of the optic disc; fundus fluorescence angiography shows low fluorescence or slow or no fluorescence filling of the optic disc; Raynaud’s phenomenon in the hands and feet. 2, posterior segment ischemic optic neuropathy manifestations and signs Sudden decrease in visual acuity with visual field defects; no headache or eye pain; normal fundus or slightly pale optic disc nasal side with clear borders; age older than 40 years, often with hypertension, hypotension, atherosclerosis or changes in blood composition; less than 40 years old mostly with Raynaud phenomenon, or history of trauma or panic, etc.