Causes of Central Retinal Vein Occlusion

Although the process of central retinal vein occlusion has been extensively studied, no one yet understands exactly what causes this problem. It is known that it usually occurs in adults over 55 years old, but it may occur in young adults as well. It is also known that patients with central retinal vein occlusion generally have a higher rate of high blood pressure than that seen in the general population, but the occurrence of a vein occlusion is not related to episodes of uncontrolled blood pressure. Patients with vein occlusions tend to have other associated vascular problems as well, such as arteriosclerosis. These findings do not explain why this disease also occurs in young people. Your physician may want to do other tests on you in order to find out if you have any other, associated medical problems. The degree of suspicion for these conditions depends on other symptoms and findings. Generally speaking, these lab tests are not usually helpful in treating a vein occlusion, but under some circumstances they may be useful in discovering other, treatable conditions.

Treatment of Central Retinal Vein Occlusion

The most frustrating aspect of this condition is that there is no treatment for a central retinal vein occlusion. Many investigators have studied this problem and attempted treatments without success. Periodically there are claims or success made for one medication or another, but no treatment has been proved effective under scientific testing conditions. Scientists have tried to thin the blood and improve the flow with various blood thinners (anticoagulants) such as aspirin, coumadin and heparin. They have tried using the same "clot busting" agents that are used successfully in heart attacks and strokes, such as TPA and streptokinase. They have tried to lower the pressure in the eye to dilate blood vessels and promote better flow. They have surgically tried to create alternative blood flow channels. None of these approaches has had any real success. One simply has to wait for the body to reopen the vein on its own. It will do so, but it may take anywhere from a few months to a few years for the vein occlusion to completely resolve.

Complications

Several complications can occur that may make the central vein occlusion more troublesome.

Macular edema was mentioned earlier. This condition is caused by fluid leaking from damaged blood vessels into the central retina. For many years it was thought that laser treatment played a useful role in treating macular edema. However, in recent years, a major scientific study demonstrated conclusively that laser was of no benefit in resoling or improving macular edema.

Neovascular glaucoma is caused by abnormal blood vessels growing on the iris and causing the pressure to build up inside the eye. If this problem is detected early, then it can be successfully treated with laser therapy. Interestingly, studies have shown that the success for laser is higher if the treatment is not given preventatively. That is, it seems best to wait until the problem has actually begun, rather than to treat ahead of time in anticipation of problems. Practically speaking that means a patient with a central retinal vein occlusion will need to be examined carefully about every 4 - 6 weeks during the first six months after diagnosis in order to catch the problem on time. Your physician may also diagnose this using a test called a fluorescein angiogram. This involves injecting a dye into an arm vein and taking photographs of the retina as the dye circulates through it. This test will give your ophthalmologist information about the health of the circulation inside your eye.

Retinal neovascularization is the growth of abnormal new blood vessels onto the retina in response to poor circulation. These abnormal vessels can bleed or cause severe scarring of the retina. The can also be treated with heavy laser treatment. Laser treatment should be started if and when the problem is first noted.

Visual Outcome

Unfortunately, central retinal vein occlusion is a very frustrating problem and final vision is often not very good. The visual outcome is not improved by any treatment since there is no way to alter the natural progression of the vein occlusion itself. It is important for your physician to monitor the situation carefully and to administer appropriate laser treatment if complications arise. However, the vision may or may not return on its own. We do have some predictors of outcome. In particular, the vision the patient has when first seeing the eye doctor is a good predictor of the eventual visual acuity. The good news is that is relatively rare to get a central retinal vein occlusion in the fellow eye.

Although a central retinal vein occlusion can cause permanently poor vision in the affected eye, it is important to follow your ophthalmologist’s advice and keep the follow-up appointments. The complications of this disease are treatable and, left untreated, they can lead to even worse vision. It is also important to keep any appointments your ophthalmologist may make with your primary care physician. Treating an associated condition can often be very important.

Find out More:
	— Retina Services.