Retinal Vein Occlusion

Retinal vein occlusion (RVO) happens when a small vein in your eye's retina becomes blocked, preventing blood from draining properly. This blockage causes blood and fluid to leak into the retina, leading to swelling and damage. RVO can cause sudden, painless blurry vision or vision loss in one eye, and prompt medical attention is important.

What is Retinal Vein Occlusion?

Retinal vein occlusion (RVO) occurs when a vein in the retina, the light-sensitive tissue at the back of your eye, becomes blocked. This blockage prevents blood from flowing out of the retina, causing blood and fluid to leak into the surrounding tissue. This leakage leads to swelling and damage, which can affect your vision.

The retina is crucial for sight, converting light into signals sent to the brain. When a retinal vein is blocked, it's like a drainpipe backing up, causing fluid to build where it shouldn't be. This fluid buildup, called macular edema, can damage the macula, the part of the retina responsible for sharp, central vision. There are two main types of retinal vein occlusion. A central retinal vein occlusion (CRVO) involves the main vein draining the entire retina. A branch retinal vein occlusion (BRVO) affects a smaller vein that drains only a portion of the retina. The type of RVO often determines the severity and extent of vision loss. Both types can lead to serious vision problems if not managed. The blockage can reduce the oxygen supply to the retina, further damaging cells and potentially leading to the growth of abnormal blood vessels, which are fragile and can bleed. These new vessels are called neovascularization.

Symptoms

The most common symptom of retinal vein occlusion is a sudden, painless change in vision in one eye. This can range from blurry vision to partial or complete vision loss. These vision changes may appear suddenly over hours or days and can vary in severity depending on which vein is affected and how much fluid leaks.

You might notice that your vision becomes blurry, distorted, or that you have blind spots in your field of vision. For example, you might struggle to read or recognize faces with the affected eye. The changes are usually not accompanied by pain, which can sometimes make people delay seeking help. The specific symptoms you experience depend on whether a central or branch vein is blocked. If a central retinal vein is affected, vision loss tends to be more widespread and severe. If a branch retinal vein is blocked, the vision changes might be more localized, affecting only a part of your vision. Sometimes, the vision changes can be mild at first and gradually worsen. In other cases, the vision loss can be very sudden and significant. It is important to remember that any sudden change in your vision should be evaluated by an eye doctor promptly.

Causes & risk factors

Retinal vein occlusion occurs when a retinal vein hardens or narrows, often due to underlying health conditions that affect blood vessels. Key risk factors include high blood pressure (hypertension), high cholesterol, and diabetes. Age is also a significant factor, with most cases occurring in people over 50 or 65.

The primary cause of RVO is often the hardening and narrowing of arteries (atherosclerosis), which can press on and block nearby retinal veins. This is why conditions that damage blood vessels throughout the body are closely linked to RVO. Several medical conditions increase your risk. High blood pressure (hypertension) is a major risk factor because it can damage blood vessel walls over time. Similarly, high cholesterol can contribute to atherosclerosis, making blockages more likely. Diabetes also harms blood vessels, increasing the risk of RVO. Other risk factors include glaucoma, a condition that increases pressure inside the eye, and certain blood clotting disorders that make your blood more likely to clot. Smoking is also known to damage blood vessels and increase the risk. Your risk also increases with age, particularly for those over 50 or 65 years old.

How it's diagnosed

Retinal vein occlusion is diagnosed through a comprehensive eye exam performed by an eye doctor. This typically includes dilating your pupils to get a clear view of your retina. Specialized imaging tests, such as optical coherence tomography (OCT) and fluorescein angiography, are also used to confirm the diagnosis and assess the extent of damage.

During the eye exam, the doctor will look for signs of a blocked vein, such as bleeding, swelling, and abnormal blood vessels in the retina. They will also check your vision and eye pressure. Dilating your pupils with eye drops allows the doctor to see the back of your eye more clearly. Optical coherence tomography (OCT) is a non-invasive imaging test that uses light waves to create detailed cross-sectional images of your retina. This helps the doctor identify and measure any swelling in the macula (macular edema), which is a common complication of RVO and a major cause of vision loss. Fluorescein angiography involves injecting a special dye into a vein in your arm. The dye travels to your eye, and a camera takes pictures as it moves through the retinal blood vessels. This test helps to identify blocked vessels, areas of leakage, and any abnormal new blood vessel growth (neovascularization).

Treatment options

Treatment for retinal vein occlusion focuses on reducing swelling, preventing new abnormal blood vessel growth, and managing underlying health conditions. Common treatments include injections of anti-VEGF medications or steroids into the eye. Laser treatment may also be used to seal leaking vessels or destroy abnormal ones.

One primary treatment involves injections of anti-VEGF (vascular endothelial growth factor) medications, such as ranibizumab or aflibercept, directly into the eye. These medications help to reduce the leakage of fluid and blood vessels, thereby decreasing macular edema and improving vision. Injections are usually given regularly over time. Steroid medications, often delivered as an implant (like a dexamethasone implant) injected into the eye, are another option. Steroids work by reducing inflammation and swelling in the retina, which can also help to improve vision. Like anti-VEGF injections, steroid treatments may need to be repeated. Laser treatment (photocoagulation) may be used in specific situations. For example, if abnormal new blood vessels (neovascularization) grow on the retina or iris, a laser can be used to destroy them and prevent bleeding or glaucoma. Laser treatment can also be used to seal leaking blood vessels in some cases of branch retinal vein occlusion. In rare cases, surgery called a vitrectomy might be considered, especially if there is significant bleeding into the vitreous gel (the clear gel that fills the eye) that does not clear on its own. Managing underlying conditions like high blood pressure, diabetes, and high cholesterol is also a crucial part of the overall treatment plan to prevent further damage or recurrence.

Recovery & outlook

The recovery and outlook for retinal vein occlusion vary widely, depending on the type, severity, and promptness of treatment. Some people may recover good vision, while others experience permanent vision loss. Early diagnosis and consistent treatment, along with managing underlying health conditions, can significantly improve outcomes and reduce complications.

Vision improvement can occur, but it is not guaranteed. For some individuals, particularly those with milder branch retinal vein occlusions, vision may improve spontaneously or with treatment. However, many people will experience some degree of permanent vision loss, especially if the macula was severely affected or if treatment was delayed. Potential complications of RVO include persistent macular edema, which is ongoing swelling that continues to blur vision. Another serious complication is the growth of abnormal, fragile blood vessels (neovascularization) that can bleed into the eye or lead to a type of glaucoma called neovascular glaucoma, which can cause pain and further vision loss. Regular follow-up appointments with your eye doctor are essential to monitor your condition, assess the effectiveness of treatment, and manage any complications. Adhering to your treatment plan and actively managing risk factors like high blood pressure and diabetes are critical steps in preserving your vision and preventing future episodes or worsening of the condition.

When to see a doctor

You should see an eye doctor immediately if you experience any sudden changes in your vision. This includes sudden blurry vision, blind spots, or any degree of vision loss in one eye, even if it is painless. Prompt medical attention is crucial for diagnosing retinal vein occlusion and starting treatment to help preserve your vision.

Do not wait to see if your symptoms improve on their own. Sudden vision changes can be a sign of a serious eye condition like retinal vein occlusion or other urgent issues that require immediate evaluation. The sooner a diagnosis is made and treatment begins, the better the chances of preserving your vision. Even if the vision changes seem mild or intermittent, it is important to get them checked. Early detection can prevent more severe and permanent vision loss. Your primary care doctor can refer you to an ophthalmologist (an eye medical doctor) or you can seek care directly from an eye specialist. If you have known risk factors for retinal vein occlusion, such as high blood pressure or diabetes, it is especially important to be vigilant about any changes in your vision and to attend regular eye check-ups as recommended by your doctor.

Frequently asked questions

Can retinal vein occlusion cause blindness?

Retinal vein occlusion can lead to significant vision loss, and in severe cases, it can cause blindness in the affected eye, especially if left untreated or if complications like neovascular glaucoma develop.

Is retinal vein occlusion preventable?

While not always entirely preventable, managing underlying risk factors like high blood pressure, diabetes, and high cholesterol can significantly reduce your risk of developing retinal vein occlusion.

How long does vision take to improve after treatment?

Vision improvement after treatment for retinal vein occlusion varies. Some people may see improvement within weeks to months, while for others, it may take longer or vision may not fully recover.

Are eye injections painful?

Before an eye injection, your doctor will use numbing eye drops to minimize discomfort. You might feel some pressure or a mild stinging sensation, but the procedure is generally well-tolerated.

Can retinal vein occlusion happen in both eyes?

Retinal vein occlusion usually affects only one eye. However, having RVO in one eye can slightly increase your risk of developing it in the other eye, especially if underlying risk factors are not well-controlled.

What is the difference between CRVO and BRVO?

Central retinal vein occlusion (CRVO) affects the main retinal vein, often leading to more widespread and severe vision loss. Branch retinal vein occlusion (BRVO) affects a smaller vein, typically causing more localized vision changes.

Sources

• MedlinePlus — Retinal Vein Occlusion
• Mayo Clinic — Retinal Vein Occlusion
• Cochrane Library — Retinal Vein Occlusion