Central retinal artery occlusion (CRAO) is an uncommon condition that can cause sudden, irreversible, severe unilateral vision loss. It usually occurs in individuals over the age of 65 and accounts for 1 in 10,000 outpatient ophthalmology visits.

With acute blockage of blood flow through the central retinal artery, profound vision loss ensues. A patient typically presents with sudden unilateral painless vision loss. There may be a history of amaurosis fugax in 10% of patients.   

Embolism is the most common cause of CRAO, usually originating from the carotid arteries or the heart. Other causes include inflammation (including giant cell arteritis), vessel spasm, thrombosis, hypercoagulable state, hypertensive retinal necrosis, increased intraocular pressure, hemorrhage under an atherosclerotic plaque, and dissecting aneurysm within the central retinal artery.  

Without intervention, a CRAO will lead to blindness in the affected eye. Experimental studies have shown that after only 4 hours, an obstruction of the central retinal artery can result in massive irreversible cell death and retinal necrosis. Even with immediate treatment, the prognosis is poor, with only 21% to 35% of eyes retaining useful vision. Most of those who recover useful vision have a cilioretinal artery that preserves the central macula function.