What Is It?
The retina is the light-sensitive layer at the back of the eye that is responsible for vision. Blood circulation to most of the retina's surface is through only one artery and only one vein. If either blood vessel or one of their smaller branches is blocked, blood circulation to the retina can be significantly disrupted. The blockage is called an occlusion. When this happens, the affected eye typically loses vision, often suddenly. The condition is painless.
Symptoms
The primary symptom of retinal artery occlusion is a sudden, painless, persistent, substantial loss of vision in one eye. In about 10% of those affected, this loss of vision is preceded by one or more episodes of a condition called amaurosis fugax. Amaurosis fugax is a temporary episode of decreased vision, usually lasting no more than 10 to 15 minutes, that is sometimes described as "closing a curtain" on one eye.
Although retinal vein occlusion also causes painless loss of vision, this vision loss sometimes develops gradually over several days or weeks rather than suddenly. Also, depending on the extent of retinal damage, some people have only minimal blurring of vision, while others have more substantial vision loss.
Prevention
Since many cases of retinal vessel occlusion are related to high blood pressure, atherosclerosis or diabetes, it may be possible to prevent this eye problem by controlling your blood pressure, cholesterol level and blood sugar. Also, all diabetics should have a thorough eye examination through dilated pupils at least once a year.
To help prevent retinal artery occlusion related to traumatic eye injuries, always wear appropriate protective eye gear (goggles, face shield, face mask) at work and while playing sports. Also, remember to use a seat belt whenever you ride in a car to prevent your face and eyes from hitting the dashboard during a collision.
Oral contraceptives have been linked to some cases of retinal vessel occlusion. Ask your doctor about your risk of this rare side effect before you begin taking birth control pills.
Treatment
Treatment depends on the type of occlusion.
Retinal Artery OcclusionTreatment focuses on increasing blood flow to the retina, while trying to dislodge the thrombus or embolus from the blocked artery. Options include:
* Ocular massage — The doctor uses his or her finger to apply pressure to your eye through your closed eyelid.
* Breathing carbogen — By breathing this mixture of 95% oxygen and 5% carbon dioxide, you may be able to increase the flow of blood and oxygen to your retina.
* Rebreathing carbon dioxide — If carbogen is not available, the doctor may ask you to breathe into a paper bag to increase the amount of carbon dioxide in your blood. The increased level of carbon dioxide should dilate (widen) the arteries in your retina, increasing blood flow.
* Anterior chamber paracentesis — An eye specialist uses a needle to remove a few drops of fluid from inside your eye. This decreases the pressure within your eye, making it easier for blood to flow through your retinal artery.
* Experimental therapies — These include injection of a clot-dissolving medication directly into the eye's circulation, administration of vasodilators (medications that widen blood vessels), exposure to hyperbaric oxygen and destruction of retinal emboli with lasers.
In rare cases, when retinal artery occlusion is caused by temporal arteritis rather than a thrombus or embolus, treatment involves long-term treatment with high-dose corticosteroid medications.
Retinal Vein OcclusionTreatment depends on the extent of blockage:
* Partial blockage — When only a small branch of the central retinal vein is blocked, sealing the damaged area with a laser (laser photocoagulation) may improve vision.
* Total blockage — When the entire central retinal vein is blocked, there is no effective treatment. However, laser photocoagulation may be used to prevent complications, such as glaucoma.
