Retinal Vein and Artery Occlusions

I. What is a Central Retinal Vein Occlusion?
Central Retinal Vein Occlusion (CRVO) is a cause of painless vision loss throughout the field of vision, often worse centrally. It may also occur with minimal symptoms. Blood flow in the main vein draining the retina is blocked or reduced. We sometimes look for associated symptoms. If vision is poor, we rarely do laser to improve vision. If vision is severely affected, we sometimes do laser to prevent a painful glaucoma. Treatment guidelines have been developed by national controlled clinical trials to stop bad blood vessels from growing in the eye.

Central Retinal Vein Occlusion (fluorescein angiogram) Click to Enlarge

Central Retinal Vein Occlusion (fundus photo - same patient) Click to Enlarge

Obstruction of the Central Retinal Vein
In CRVO, there is usually an obstruction of the central retinal vein of the optic nerve. The vein may be pinched, like stepping on a garden hose, cutting off the flow. The retina may bleed, die, or become congested and swollen. A leading cause of blurred vision in CRVO is macular edema. If the central retina dies, vision cannot be improved with laser. If the retina has not died, there is about a 33% chance of visual improvement, 33% chance of worsening, and about 33% stay the same.


II. What are the causes of a Central Retinal Vein Occlusion?
The cause of CRVO is usually undiscovered. However, it is more likely to occur in people with a history of hypertension, diabetes, glaucoma, ocular inflammation, or carotid artery disease. It may also occur in hyperviscosity syndromes, where the blood is too thick. The conditions associated with CRVO are detected with complete ocular and general examinations, and with laboratory and blood tests. Their treatment may reduce the risk of vein occlusion in the fellow eye.


III. What is a Branch Retinal Vein Occlusion?
Branch Retinal Vein Occlusion (BRVO) is a cause of painless vision loss in the upper, lower, or central field of vision. It may also occur with no symptoms. Occlusion occurs when blood flow in a vein is reduced or blocked. In BRVO, there is usually an artery crossing over the retinal vein at the point of obstruction. This can pinch the vein, like stepping on a garden hose, and thereby cutting off blood flow. The area of retina, which drained through this vein, may become congested or swollen. Areas of the retina may bleed or die. Sometimes the obstruction is reversible, and sometimes it is irreversible.

The leading cause of blurred vision in BRVO is macular edema. This is swelling of the central retina caused when blood can't flow through the blocked vein, so fluid leaks into the retina.

Branch Retinal Vein Occlusion (fluorescein angiogram) Click to Enlarge

Branch Retinal Vein Occlusion (fundus photo - same patient) Click to Enlarge

IV. What causes a Branch Retinal Vein Occlusion?
The most common cause of BRVO is no cause. However, it may be more likely to occur in people with a history of hypertension, diabetes, glaucoma, ocular inflammation, or carotid artery disease. BRVO may also occur in hyperviscosity syndromes, where the blood is too thick. The conditions associated with BRVO are detected with complete ocular and general examinations, and with laboratory and blood tests. Blood tests are most often done for those under 55 years.


V. Is there treatment for a Branch Retinal Vein Occlusion?
If there is macular edema present, laser increases the chances for vision improvement by over 60%. If there is new blood vessel growth and vitreous bleeding takes place, scatter laser reduces the chance of severe visual loss in over 85%. The blood usually clears spontaneously.

Laser is a light focused to a pinpoint. It can dry swollen retina, or burn retina that has new blood vessels. Laser for macular edema is very brief. A grid pattern of laser is used if vision is 20/40 or worse, for month with macular edema. Laser is a simple outpatient procedure done in the office. You can return to normal activities the next day. Occasionally, laser must be repeated, if there is still swelling after 3 to 4 months following laser treatment.

Retinal Disorders

Diabetic Retinopathy
Age-Related Macular Degeneration
Retinal Vein and Artery Occlusions
Macular Hole
Macular Pucker
Retinal Tears and Detachments
What is Fluorescein Angiography?
What is Photodynamic Therapy?
What is ICG Angiography?
What is optical coherence tomography?

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