Branch retinal vein occlusion is a blockage to one of the veins that drains blood out of the retina. The blockage leads to a build-up of pressure on the vein causing haemorrhage and leakage of fluid out of the vein into the retina.
In most cases the blockage occurs at a point where an artery and vein cross. This crossing combined with damage to the vascular wall due to high blood pressure, high cholesterol, smoking or diabetes causes increased pressure on the vein.
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After a BRVO, there are 2 types of complications that can occur:
Macular Oedema
Occurs when the blocked vein is near the macula. The leakage of fluid and bleeding causes the macula to swell leading to blurred vision and parts of vision missing.
Neovascularisation
In severe cases of BRVO blood flow is sufficiently impaired such that the body responds by growing new, abnormal blood vessels. These vessels may grow into the vitreous (gel-like part of the eye) and can bleed causing a significant decrease in vision.
Frequently Asked Questions
What are the symptoms?
Symptoms of BRVO vary depending on the site of the blockage. If the blockage doesn’t involve the macula (central part of your vision), you may not be aware that you have the condition.
If the blockage is close to the macula, you may experience:
- A sudden painless decrease or blurring of vision
- Part of your vision mission or black spots appearing in your vision.
- Distortion of vision (straight lines appearing bent)
What are the risk factors?
As the condition is most commonly caused by the crossing of arteries and veins, your anatomy determines your predisposition for this condition. Glaucoma is a risk factor for BRVO Other risk factors are aging, high blood pressure, high cholesterol diabetes and smoking.
What treatments are available?
Several treatments are available to deal with the macular oedema and prevent neovascularisation (new blood vessels forming).
These include:
Laser Photocoagulation
If you have macular oedema, laser is focused on small areas around your macula where the leakage has occurred. If you are at risk of neovascularisation, laser is applied to areas of the retina that are not receiving oxygen. In these cases, large areas of the retina are lasered to prevent vision loss associated with the growth of abnormal new blood vessels.
Injections with Avastin
Avastin is a drug that is given via an intravitreal injection (injection into the vitreous of the eye). It is used to stop the factors responsible for the growth of new blood vessels in the eye and also to reduce the swelling of the macula. Repeat injections are often required (usually 4-6 injections) with around 6 weeks between injections. Often a combination of Avastin injections and laser is required to optimally restore the macula.
Are there any preventative measures I can take?
- Keep your blood pressure in the normal range and take blood pressure lowering medication if required.
- Reduce your intake of saturated fats
- Optimize control of diabetes and high cholesterol/lipids.