Retinal vein occlusion (RVO) is a chronic eye condition that can lead to sudden vision loss.
RVO is the second most frequent cause of visual loss from diseases affecting the blood vessels of the retina. Patients with RVO can experience blurred vision, spots (known as floaters), distorted vision and even sudden and complete loss of vision.
There are two main types of RVO:
- Central retinal vein occlusion (CRVO): CRVO is caused by an obstruction of the central retinal vein.
- Branch retinal vein occlusion (BRVO)
BRVO occurs when one or more of the branches of the central retinal vein are obstructed and is up to six times more common than CRVO.
Globally, 16.4 million people are affected by RVO, 13.9 million people with BRVO and 2.5 million with CRVO. While the risk of developing RVO increases with age, many RVO patients are still of working age. In fact, one in six patients is younger than 55.
A blockage in the retina that can lead to significant visual impairment
RVO occurs when there is a blockage in the blood vessels of the retina, the light-sensitive nerve tissue lining the back of the eye. If the blockage is not resolved, it can result in a number of complications. One such complication is a reduction of the oxygen supply in the retina, leading to an increase in the production of the protein vascular endothelial growth factor (VEGF). This can cause the formation of leaky blood vessels responsible for swelling in the macula, the center of the retina responsible for seeing fine details. This can occur at any stage of RVO. In late-stage disease when blood flow is severely impaired, an increase of VEGF can also result in an abnormal and uncontrolled blood vessel growth. The most common cause of vision loss in patients with RVO is swelling in the macula (macular edema).
The ultimate cause of RVO is not well understood but various factors may contribute to the risk of developing clots in the retinal veins: advancing age, history of high blood pressure, glaucoma, diabetes, high cholesterol, cardiovascular disease and smoking.
Early identification of RVO is critical to ensure the best outcomes
Delaying diagnosis and treatment may result in irreversible damage to the retina which may limit improvements in vision over the long-term. In cases of sudden or gradual vision loss, the retina must be examined via an ophthalmoscope. By shining a light into the back of the eye, the doctor is able to look through the pupil at the small vessels in the back of the eye. If the patient suffers from RVO, the doctor will see dilated and winding veins bulging from blood backup, bleeding into the retina, or swelling due to the leakage of fluid.
Appropriate treatment can allow patients to regain their vision
There is generally no accepted medical therapy to treat retinal blockages so unless they resolve themselves, physicians must continuously monitor RVO patients for disease progression and treat any sight-threatening complications. Anti-VEGF therapies have become the standard of care for RVO, allowing patients to not only maintain their vision but also to have their vision restored. Anti-VEGF therapies block the growth factor that stimulates the swelling and subsequent leakage as well as the growth of new abnormal blood vessels. Prior to anti-VEGF therapies, available treatment options, including laser therapy, virectomy and steroids, were only able to stabilize the disease and/or provide modest visual improvements.
In 2013, Bayer’s anti-VEGF therapy was first approved for the treatment of macular edema secondary to central retinal vein occlusion (CRVO). It is now approved in many countries around the world, including the United States and Japan, for both CRVO and BRVO.
Advice for patients
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