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Branch and Central Retinal Vein Occlusions

Retinal Vein Occlusions

Vein occlusions are the second only to diabetes in producing disease of the vessels of the retina. There are two basic types of vein occlusion, branch retinal vein occlusion (BRVO), in which one of the branches of the main vein are blocked, and central retinal vein occlusion (CRVO) in which the main vein of the eye is blocked.

The complications of a BRVO or a CRVO are what you might expect from the damage done to the eye. The most common cause of decreased vision is leakage of fluid from blocked vessels, macular oedema. In many patients this will clear on its own over time, however, if it doesn't do so within three months, laser, injections or surgical therapy may be needed.

A second problem is the development of new vessels. These grow not into the damaged retina where they are needed but into the vitreous cavity. These vessels can bleed and partially or totally fill the vitreous cavity, blocking off vision.

 

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Retinal Vein Occlusions
Vitrectomy Surgery

Treatment of Branch and Central Vein Occlusions

Laser, intraocular drug injections or vitrectomy surgery may be needed, although if it has only just happened then often waiting for three months is not unreasonable to see if it improves by itself.

The Branch Vein Occlusion Study and the Central Vein Occlusion Study were performed to determine if and when laser photocoagulation was indicated in these diseases for macular oedema and new vessels. Laser was found to be advantageous over no treatment in the treatment of macular oedema in BRVOs but not CRVOs and for specific indications with neovascularization (retinal and iris) in each disease. Laser works (presumably) by causing leaking vessels to stop leaking and by decreasing the need for oxygen in damaged areas (thus decreasing the need for new vessels). Laser does not, however, open the damaged vessels and return normal blood flow to the retina.

Several surgical treatments of vein occlusions are possible although none can be guaranteed to restore vision. All of them involve vitrectomy and different techniques can be used following the vitrectomy part of the operation to try to improve vision.

In patients who have macular oedema, injections into the eye of drugs such as Avastin and triamcinolone have been shown to improve vision.

Finally, a devastating complication, particularly for CRVOs, is the development of new vessels on the surface of the iris called rubeosis. These vessels can block the outflow channels of the eye (trabecular meshwork) and cause a very hard to control glaucoma (neovascular glaucoma). Patients are followed very closely for the first six months after a CRVO to watch for this problem.

General Health Implications of Retinal Vein Occlusions

Anyone who has had a retinal vein occlusion must make sure that they are not at risk of having blockages of other veins or arteries in other parts of their body, as that could cause even more serious conditions such as heart attacks or strokes. The same risk factors such as high cholesterol, high blood pressure, smoking, poor diet, lack of exercise and diabetes are all risk factors both for retinal vein occlusions and for other vascular events elsewhere in the body. Hence we suggest you make contact with your GP to look for these things if you haven’t already done so.