Retinal vein occlusion is a sudden blockage in the blood vessels of the eye that can steal your vision without warning. While there’s no way to reverse the blockage itself, understanding the condition and seeking prompt treatment can help protect your remaining sight and prevent further complications.

What is Retinal Vein Occlusion?

Retinal vein occlusion occurs when one of the veins that carry blood away from your retina becomes blocked. The retina is a thin layer of tissue at the back of your eye that acts like a camera film, capturing light and converting it into images that your brain can understand. When blood can’t drain properly from the retina, it backs up, causing pressure and fluid to build in the eye.^[1]

Think of it like a traffic jam in your eye’s blood vessels. When the vein gets blocked, blood and fluid leak into the retina, causing swelling and damage to the nerve cells that help you see. This backup can lead to serious complications if not treated promptly.^[2]

There are two main types of retinal vein occlusion. Central retinal vein occlusion (CRVO) happens when the main vein that drains blood from the retina becomes blocked. This type tends to cause more severe vision problems because it affects the entire retina. Branch retinal vein occlusion (BRVO) occurs when one of the smaller branch veins gets blocked. This type is more common and usually affects only part of your vision since it impacts a smaller area of the retina.^[1]

How Common is This Condition?

Retinal vein occlusion is the second most common disorder affecting the retina, with diabetic retinopathy being the first. Globally, this condition affects more than 16 million people. The numbers vary by type: central retinal vein occlusion affects between 1 and 4 in every 1,000 people, while branch retinal vein occlusion affects between 6 and 12 in every 1,000 people.^[1]

This is not a rare condition. In fact, some sources describe it as the third most common condition that retina specialists treat. It affects less than 1 percent of adults worldwide, but the numbers increase significantly with age.^[2][7]

The condition typically strikes people in their 50s or 60s, though it can affect younger individuals as well. About 90 percent of people with retinal vein occlusion are over 50 years old, making age one of the strongest predictors of who might develop this condition.^[6]

What Causes Retinal Vein Occlusion?

The most common cause of retinal vein occlusion is hardening of the arteries, known as atherosclerosis, combined with the formation of a blood clot. When arteries become stiff and hardened from plaque buildup or aging, they can press on the veins that run alongside them. This pressure can damage the inner lining of the vein, creating conditions where a blood clot is more likely to form.^[5]

Your retinal artery and vein share a common covering, like two cables wrapped in the same protective sheath. As the artery becomes stiffer with age or disease, it can squeeze the vein next to it. This compression slows down blood flow, causing turbulence that damages the vein’s delicate inner wall. Once damaged, the conditions are right for a clot to develop and block the vein completely.^[1]

Sometimes the blockage happens because blood flow simply slows down too much. When blood moves too slowly through a vein, it’s more likely to clot, similar to how standing water becomes stagnant. This slowdown can occur for various reasons related to your overall cardiovascular health.^[1]

Who is at Risk?

Age is the single biggest risk factor for retinal vein occlusion. Being over 40 puts you at increased risk, with the condition most commonly affecting people in their 50s and 60s. However, this doesn’t mean younger people are completely safe from developing the condition.^[1]

Several medical conditions significantly raise your risk of developing retinal vein occlusion. High blood pressure, also called hypertension, is a major risk factor because it contributes to the hardening and stiffening of blood vessels throughout your body, including those in your eyes. People with poorly controlled blood pressure are much more likely to develop this condition.^[5]

Diabetes increases your risk in multiple ways. It can damage blood vessels directly and also increases your likelihood of developing other risk factors like high blood pressure and high cholesterol. Having diabetic retinopathy, which is damage to the retina caused by diabetes, further elevates your risk.^[4]

Glaucoma, a disease that causes increased pressure inside the eye, is another important risk factor. The elevated eye pressure can affect blood flow through the retinal veins, making blockages more likely. High cholesterol and smoking also increase your risk because they contribute to atherosclerosis and blood vessel damage.^[4]

Recognizing the Symptoms

The symptoms of retinal vein occlusion typically affect only one eye and can develop suddenly or gradually over hours or days. The most common symptom is blurry vision or sudden vision loss in one eye. Some people describe their vision as being cloudy or like looking through a fog. Others experience complete vision loss in part or all of one eye.^[1]

Many people notice floaters before other symptoms appear. Floaters look like dark spots, lines, or squiggly shapes that seem to float across your field of vision. They move when you try to look directly at them, making them frustrating to focus on. While floaters can be harmless in many situations, their sudden appearance or increase can signal a serious problem like retinal vein occlusion.^[7]

In more severe cases, you might feel pain or pressure in your affected eye. This usually indicates complications have developed, such as abnormally high pressure inside the eye. Some people also notice distorted or wavy vision, where straight lines appear bent or objects look misshapen.^[4]

One particularly concerning aspect of this condition is that some people have no symptoms at all until complications develop. They might not realize anything is wrong until an eye doctor discovers the problem during a routine examination. This is why regular eye exams become increasingly important as you age, especially if you have risk factors for retinal vein occlusion.^[1]

How is Retinal Vein Occlusion Diagnosed?

Eye doctors can detect retinal vein occlusion during a comprehensive dilated eye exam. This examination is straightforward and painless. Your doctor will put special drops in your eyes to dilate your pupils, making them wider. This allows the doctor to see deep inside your eye and examine your retina for signs of blockage or damage.^[12]

Several specialized tests help doctors evaluate the extent of the blockage and any complications. A fluorescein angiogram involves injecting a special dye into a vein in your arm. This dye travels through your bloodstream to the blood vessels in your eye. Your doctor then uses a special camera to take pictures as the dye moves through your retinal vessels, revealing any blockages or leaking blood vessels.^[5]

Another important test is optical coherence tomography (OCT). This test uses light waves to take detailed pictures of your retina, similar to how an ultrasound creates images but with much higher resolution. OCT can show how much swelling has developed in your retina and helps doctors monitor how well treatments are working over time.^[12]

Your doctor will also perform several other standard eye tests. These include measuring the pressure inside your eye, checking how your pupils respond to light, testing your side vision, and measuring how clearly you can see letters on an eye chart. Some doctors may also take regular photographs of your retina to track changes over time.^[5]

Because retinal vein occlusion is often related to general health problems, your doctor might recommend blood tests to check for diabetes, high cholesterol, and conditions that affect blood clotting. This is especially common in people under 40 who develop the condition, as it may indicate an underlying blood disorder that needs treatment.^[5]

How Retinal Vein Occlusion Changes Your Eye

Understanding what happens inside your eye when a vein becomes blocked helps explain why treatment is so important. When blood can’t drain properly from your retina, pressure builds up in the tiny blood vessels. This increased pressure forces fluid and blood to leak out of the vessels and into the surrounding retinal tissue.^[2]

The leaked fluid causes macular edema, which is swelling in the macula, the central part of your retina responsible for sharp, detailed vision. Think of the macula as the high-definition center of your vision that you use for reading, recognizing faces, and seeing fine details. When it swells with fluid, this detailed vision becomes blurry or distorted. Macular edema is one of the main causes of vision loss in people with retinal vein occlusion.^[1]

When your retina doesn’t receive enough oxygen due to the blocked vein, your body tries to help by releasing a protein called vascular endothelial growth factor (VEGF). While this protein normally helps blood vessels grow, too much VEGF causes problems. It stimulates the growth of new, abnormal blood vessels in your eye. These vessels are fragile and leaky, causing more fluid buildup and increasing pressure inside the eye.^[12]

These abnormal blood vessels can grow in various parts of your eye, most commonly on your iris, the colored part of your eye. This condition is called rubeosis iridis and occurs in about one in four people with retinal vein occlusion. When abnormal vessels grow on the iris, they can block the normal drainage of fluid from your eye, leading to a dangerous type of glaucoma called neovascular glaucoma. This can cause severe pain and further vision loss if not treated promptly.^[1]

Preventing Retinal Vein Occlusion

While you can’t control some risk factors like age, you can take steps to reduce your overall risk of developing retinal vein occlusion. The same healthy lifestyle changes that protect your heart and blood vessels throughout your body also help protect the delicate blood vessels in your eyes.^[5]

Managing high blood pressure is one of the most important preventive measures. If you have hypertension, work closely with your doctor to keep it under control through medication, diet, and lifestyle changes. Regular monitoring and consistent treatment can significantly reduce your risk of blood vessel damage in your eyes.^[4]

If you have diabetes, keeping your blood sugar levels well controlled is crucial. High blood sugar damages blood vessels over time, increasing your risk not only of diabetic retinopathy but also of retinal vein occlusion. Follow your diabetes treatment plan carefully, monitor your blood sugar regularly, and attend all scheduled appointments with your healthcare team.^[5]

Eating a heart-healthy diet helps protect your blood vessels. Focus on eating plenty of fruits, vegetables, whole grains, and foods high in fiber. Limit saturated fats and cholesterol, which contribute to atherosclerosis. Some research suggests that eating more fish, nuts, fruits, and vegetables may have protective effects against blood vessel diseases.^[21]

Regular exercise is another powerful preventive tool. Physical activity helps control blood pressure, maintain a healthy weight, and keep blood flowing smoothly through your vessels. Getting regular exercise doesn’t require intense workouts; even moderate activities like walking can make a significant difference.^[5]

If you smoke, quitting is one of the best things you can do for your eye health. Smoking damages blood vessels throughout your body and significantly increases your risk of retinal vein occlusion. Talk to your doctor about smoking cessation programs and medications that can help you quit for good.^[4]

Some people with certain risk factors may benefit from taking aspirin or other blood thinners to prevent blockages, though this decision should be made carefully with your doctor. These medications can help prevent blood clots but also carry risks, so they’re not appropriate for everyone.^[5]