AION is seen in which of the following conditions

ANTERIOR ISCHAEMIC OPTIC NEUROPATHY(AION) refers to ischaemic damage to the optic nerve head from occlusion of the sho posterior ciliary aeries. It is of two types : Aeretic AION - results from inflammatory and thrombotic occlusion of sho posterior ciliary aeries caused by Giant Cell Aeritis (GCA) , usually occurs in older patients (mean age 70 yrs) and accounts for only 5-10% cases of AION. Non aeretic AION - accounts for 90 - 95% cases of AION. Exact etiology of occlusion of posterior ciliary aeries causing infarction of the retrolaminar poion of the disc is not known. Risk factors include cataract surgery , HTN, diabetes , drugs (sildenafil). Ref: khurana 6th edition page no.318