Central Retinal Artery Occlusion
When people are cautioned to maintain a healthy lifestyle they usually think it is solely to prevent obesity or heart disease. Most people do not realize that our eyes are as dependent on our life choices as other organs in the body. As we age a natural plaque begins to form in our arteries just as plaque forms on our teeth if we don’t brush them. This happens to everybody but only escalates into a problem if the amount of plaque creates a loss of elasticity and hardens onto the arterial wall. These deposits are made up of calcium cholesterol or fatty tissue and eventually may cause a blockage of the inner wall of the artery. The following risk factors increase the production of plaque along the arterial wall:
- family history of artery hardening (atherosclerosis)
- high cholesterol
- high blood pressure
A complication with heavy plaque build-up is the potential for “debris”; some hardened pieces of plaque get knocked off the wall by flowing blood and then enter into the bloodstream.
A central retinal artery occlusion (CRAO) occurs when the central retinal artery is blocked by a clot or debris (emboli). The debris most often originates in the carotid artery and sometimes from a heart clot. When the debris lodges in the artery oxygen is effectively cut off causing total visual loss of the retina. The retina is the light-sensitive layer of tissue that lines the back of the eyeball sending visual impulses through the optic nerve to the brain The retina plays a very important role in the eye and as such it requires a lot of blood to function properly. When it is deprived of it even for a short period of time it’s likely that vision damage incurred during the occlusion is permanent.
CRAOs most commonly occur in people between 50 and 80 years old. There is often a history of systemic illness like hypertension heart valve abnormalities carotid artery disease or diabetes. The patient usually presents with a sudden onset of profound unilateral painless visual loss. A less visually-threatening condition is known as a branch retinal artery occlusion (BRAO) whereby there is an obstruction of one of the smaller retinal arteries branching from the central retinal artery. In this case there is only partial visual loss but both situations require immediate medical attention.
Currently treatment options for both CRAOs and BRAOs are few and usually unsuccessful. Unless the occlusion can be diagnosed and treated in the first 90 minutes vision damage will be permanent. By the time someone who has suffered a CRAO realizes something is wrong he/she arrives at the hospital too late – the retina is already damaged and difficult to fix. Anyone who has had a CRAO is at an increased risk for stroke and heart attack. For this reason and to prevent further damage it is imperative to visit your general practitioner (and perhaps a cardiologist) plus your eye doctor more than once a year. On the positive side doctors are looking into laser surgery and how it may help rectify retinal damage and fix the visual impairment caused by the occlusion.