Arteries and veins course within the back of the retinal tissue that lines the back of the eye. Like elsewhere in the body, arteries bring blood into the tissue and veins move blood out of the tissues and back toward your heart. A retinal vein occlusion (RVO) is the blockage of one of those veins.
When the retinal veins become occluded, the blood flow from the eye is compromised. The back-up of blood within the retinal tissues leads to hemorrhages and swelling of the tissue. If this swelling is in the central portion of the vision, this is called macular edema and can cause serious damage to the vision. Some patients may notice blurred or distorted vision as a result of an RVO. However, since some people with RVO may not notice any symptoms, it is important to have your eyes checked regularly.
If your primary eye doctor discovers an RVO in your eye, you will often be referred to a retinal specialist. A retinal specialist is an eye MD who has specialized training in the diagnosis, management, and surgery of conditions that involve the retina. A detailed examination of the back of the eye (retina) will be performed using several office instruments. The visual field may be tested to determine how much of the peripheral vision has been affected. Your eye doctors may work with your primary care doctor to investigate suspected causes of RVO. For example, they may order blood tests and monitor your blood pressure.
Your retina specialist may also take high-resolution images that reveal a cross-sectional view of the retina. These images (called optical coherence tomography, or OCT) detect and measure the buildup of macular edema and can be used to monitor your response to treatment. Additionally, a fluorescein angiogram may be performed to evaluate the blood flow within the retina. A mild, water-soluble dye is injected into the arm and a sequence of video or pictures of the retina are taken with a special filter, revealing circulatory or tissue problems.
This combination of examination and testing can help determine the type and severity of RVO. If the entire venous circulation of the retina is occluded, this is termed a central retinal vein occlusion, or CRVO. When the blockage happens in one of the smaller branch veins of the retina, this is known as a branch retinal vein occlusion, or BRVO. Examination of the pupils, visual fields, and angiographic images help to determine if the occlusion is severe enough for blood flow into the eye to be affected as well, a condition called ischemia.
Anyone can get a retinal vein occlusion, even young otherwise healthy individuals. However, RVO tends to happen to people who are over 50 years old. Hypertension (high blood pressure) is the systemic condition most commonly associated with RVO. Diabetes, hardening of the arteries, and glaucoma also play a role. Additionally, obesity, smoking, oral contraceptive use, and abnormally thick blood (hypercoagulability) may add to the risk of venous occlusion.