RETINAL VASCULAR DISEASES
Ocular Ischemic Syndrome
Ocular ischemic syndrome (OIS) is a state of ocular hypoperfusion caused by vascular disease. The most common cause is an ipsilateral atherosclerotic carotid artery disease, producing stenosis. Dissecting carotid aneurisms as well as giant cell arteritis have also been reported as causing critical stenosis of internal or common carotid arteries. When stenosis reaches 70% of the vascular lumen, flow abnormalities can be demonstrated. When stenosis reaches 90% of the carotid lumen, ipsilateral central retinal artery perfusion pressure is reduced by 50%. In rare cases, OIS can be caused by ipsilateral ophthalmic artery obstruction. A case of chronic central retinal artery occlusion may also mimic the findings of OIS.
OIS is more common in males, with a male to female ratio of 2:1. The mean age of diagnosis is 65 years,...