BRANCH RETINAL VEIN OCCLUSION

What is a branch retinal vein occlusion?
This condition is the blockage of a vein by a clot, at the site where the artery and vein cross. Arteries are blood vessels which carry oxygenated blood from the heart to all parts of the body, including the retina. Veins are blood vessels which carry deoxygenated blood from all parts of the body back to the heart.

What causes this condition?
• In 50% of patients, it is related to hypertension induced arteriosclerosis (narrowing and hardening of the arteries.)

• It often affects people in their 50’s and 60’s.

DIAGNOSIS
How is this condition diagnosed?
Several clinical signs found by the physician upon retinal examination support the diagnosis of branch retinal vein occlusion. These include:
• Bleeding
• Swelling
• Engorgement of Veins

Fluorescein Angiography may be performed to confirm the diagnosis and to evaluate the extent of the affects of the blockage on the retina. Fluorescein angiography is a test in which a water soluble dye is injected into a vein in the arm. The dye quickly passes through the circulation to the eye and serial photographs are taken to examine retinal circulation.

What are the possible complications associated with this condition?
Swelling in the macula (the center of the retina, used for central vision.) The blockage of the vein slows the rate at which blood is able to leave the eye. This may cause some pooling of extra fluid in the center of the retina. The “fluid” may be reabsorbed naturally by the body or may require treatment with laser, medication or surgery.

A rarer, but more dangerous, complication is the formation of abnormal new blood vessels (neovascularization) which may grow on the iris (the colored part of the eye) or on the retinal surface. These abnormal vessels may bleed easily, causing further visual loss. Once detected, they should be treated with laser.

TREATMENT
Laser Treatment:
If vision remains blurry due to persistent swelling after the blood clears, or if abnormal blood vessels are detected, laser may be helpful. The laser is usually the primary treatment for macular edema. The laser is a bright, highly focused beam of light which can seal some of the leaking vessels. A large, multi center research study had reported the benefit of laser treatment for patients with swelling in the macula. Patients were found to have a more likely chance of visual improvement with laser treatment.

Kenalog Injection
Kenalog (triamcinalone is the generic name) is a medication which has been used for many years to treat inflammation and swelling in the eye. This medication can be given as an injection next to the eye (periocular injection), but is much more effective if injected directly into the eye (intravitreal injection).

Sheathectomy Surgery
The site of the Branch Retinal vein occlusion can often be seen clearly on examination. If this is the case, and if simpler treatments are not effective, microsurgical techniques can be used to open the sheath constricting the vein at the site of occlusion.

What type of vision can be expected to return?
In most cases, visual acuity does eventually improve somewhat after a branch retinal vein occlusion (BRVO). The recovery phase involves the natural formation of collateral vessels by the body. Imagine the area of blockage as a road block. These collateral vessels can be seen as a detour—a way for the blood to avoid the “road block” and return via an alternate route. Although many patients do experience a return of vision after a BRVO, it often is not to the level of vision before the occurrence of the occlusion. The amount of vision which returns depends upon the degree of blockage of the circulation and the amount of time required for collateral vessels to develop.

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