Branch retinal vein occlusion is a blockage of the veins that carry blood containing oxygen and nutrients away from the retina (the area at the back of the eye where images are formed). When blood circulation in the eye is blocked, fluid and blood spills into the retina.
The retina handles conversion of images and light into signals that are sent to the brain through the optic nerve. The buildup of fluids and blood plus the lack of oxygen ruins the light receptors of the macula (central part of the eye). This impairs the retina’s capacity to filter light. As a result, one’s central vision becomes blurry. In the long run, small capillaries in the macula are affected and this blocks circulation of blood in the macula leading to permanent visual loss.
Up to 30% of patients suffering from BRVO develop new blood vessels on their retina. These vessels bleed and cause more vision loss.
Also Known As
- BRVO (Branch retinal vein occlusion)
- Branch retinal occlusion
- Branch retinal vein thrombosis
- Venous retinal tributary occlusion
Causes and Risk Factors
Branch retinal vein occlusions occur when a patient’s veins are blocked due to clotting. In most cases, BRVOs occur at the intersection between a retinal vein and artery. Since these vessels share a connective tissue, in the event that the artery loses its flexibility, the vein becomes compressed.
This is the case with the hardening of arteries (atherosclerosis). The compressed vein suffers from turbulent blood flow and this promotes clotting which leads to occlusion or blockage. Such blockage results in fluid leaking into the macular and poor flow in the blood vessels that supply the macula.
People who face a higher risk of suffering from BRVO have conditions such as:
- Macular edema
- High cholesterol
- High blood pressure
Signs & Symptoms
The main symptom of branch retinal vein occlusion is blurry vision or vision loss in a small part of the affected eye or the entire eye. One may experience sudden vision loss or gradual vision loss. Some patients may develop floaters; these are dark lines, squiggles or spots in one’s vision. These are caused by blood leaking into the retinal vessels. In most cases, BRVO affects one eye.
The diagnosis of BRVO is done mainly through an eye exam. The exam shows the blood vessels that are leaking into the patient’s retina. It also shows retinal edema and twisted/thickened blood vessels. Imaging tests also help in diagnosing BRVO. These tests provide images of fluid leaking from the abnormal or damaged retinal vessels. This demonstrates any of the following:
- Retinal neovascularization (growth of new blood vessels)
- Edema (swelling that contains fluid)
- Venous stasis (congestion of circulation)
- Ischemia (insufficient blood supply)
Optical coherence tomography (OCT) displays detailed images of the center part of the retina. It allows the eye professional to detect macular edema.
Fluorescein angiography (FA) is mostly used to detect the flow of blood vessels and BRVO. After BRVO is found, OCT provides a detailed analysis of the presence and severity of macular edema.
Treatment is aimed at stabilizing vision and preventing swelling of the macula.
Intraocular (eye) injections of anti-vascular endothelial growth factor (VEGF) drugs are administered to stop the development of abnormal blood vessels in the patient’s eye. The three main anti-VEGF drugs are Avastin, Lucentis and Eylea. These drugs also decrease leakage. The eye doctor will give the patient local anesthetic eye drops before injecting the drugs.
Another intraocular injection administered when anti-VEGF drugs fail is Ozurdex, a steroid implant. The implant is invisible to the patient. The effect of this drug lasts for 6 months and so has to be administered for at least 3 years. The drug reduces inflammation that causes waterlogging.
Laser treatment is used alongside anti-VEGF treatment in severe cases. Laser therapy involves applying laser pulses to the patient’s macula. A good number of patients who undergo laser treatment experience improved vision.
Injections expose patients to a small risk of infection in the eyeball and serious complications regardless of the drug that is injected into the eye. These complications can lead to total loss of vision.
Patients who undergo the steroid implant are likely to get cataracts. Ozurdex also presents the risk of glaucoma.
Laser treatment needs to be repeated because it may fail to work the first time it is administered. It may also cause a patient to develop new blood vessels at the area of the laser burn in the future. In rare cases, it causes patients to have blind spots which worsens their vision.
Many people regain their vision after receiving treatment for retinal vein occlusion. Unfortunately, those who suffer from other eye complications may not recover. Going for regular checkups is recommended to prevent further complications.
Because this condition affects the veins, one can reduce their risk by protecting their blood vessels through observing healthy practices. A healthy dietary and lifestyle change include:
- Observing your weight
- Controlling diabetes
- Not smoking
- Cutting down cholesterol levels
- Working to lower one’s blood pressure
- Taking blood thinners such as aspirin if recommended by one’s doctor