CRAO usually occurs in people between the ages of 50 and 70. The most common medical problem associated with CRAO is arteriosclerosis, hardening of the arteries. The most common cause of CRAO is a thrombosis, an abnormal blood clot formation. Sometimes CRAO is caused by an embolus, a clot that breaks off from another area of the body and is carried to the retina by the bloodstream. The first sign of CRAO is a sudden and painless loss of vision that leaves you barely able to count fingers or determine light from dark.
Loss of vision can be permanent without immediate treatment.
Irreversible retinal damage occurs after 90 minutes, but even 24 hours after symptoms begin, vision may still be saved. The goal of emergency treatment is to restore retinal blood flow. You probably know high blood pressure and other vascular diseases pose risks to overall health, but you may not know that they can affect eyesight by damaging the veins in the eye. The blockage causes the walls of the vein to leak blood and excess fluid into the retina. When retinal blood vessels are not working properly, the retina grows new fragile vessels that leak blood into the vitreous, the fluid that fills the center of the eye.