THE CAROTID ARTERY AND THE EYE

What Is The Carotid Artery?

The two carotid (pronounced ka-rah-tid) arteries are the main arteries in the neck which supply blood to the eyes and the brain. One carotid artery supplies the right side, while the other serves the left. Because the eye and the brain share the same source of blood supply, blockages or conditions of the carotid artery can affect either or both organs.

What Happens When The Carotid Artery Is Blocked?

When the large or small branches of the carotid artery are blocked, the brain is deprived of blood and a stroke may result. Depending on the part of the brain involved and the size of the area deprived of its blood supply, the effects of a stroke may be slight or devastating. Severe effects can include paralysis of one side of the body and loss of speech. If the part of the brain having to do with vision is involved, a stroke can lead to loss of side vision.

When the ophthalmic artery (the first main branch of the internal carotid artery) or its branch (the central retinal artery) is blocked, a sudden, near-total loss of vision usually occurs. The mechanism of damage is the same in the brain and the eye. Cells die if they are deprived of blood for too long.

Is This Damage Permanent?

Not everyone who suffers a blocked blood supply to the eye or the brain has permanent damage. A temporary blockage of blood supply to the brain, called a transient ischemic attack (TIA), may result in muscle weakness on one side of the face or numbness of an arm or leg which only lasts about an hour.

A temporary blockage of blood supply to the eye, called amaurosis fugax, is a temporary loss of vision in one eye. This sometimes appears as a blacking out of all or part of your vision in that eye and may last for seconds.

Both amaurosis fugax and transient ischemic attacks are possible warnings of a serious problem involving the brain's blood supply. They should be reported to an eye doctor who may recommend further tests.

Are There Other Signs Of Carotid Artery Disease?

As part of a routine eye exam, the eye doctor may dilate the pupil to examine the retina at the back of the eye. During this procedure, conditions which may indicate an increased risk of stroke are sometimes discovered.

For instance, when the carotid artery becomes gradually blocked with fat and calcium deposits, the first signs can appear in the eye, providing critical clues to a life-threatening reduction of circulation to the brain.

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