Retinal Vein Occlusion

Retinal vein occlusion is a blockage in a small blood vessel that carries blood away from the back of your eye. This condition can cause sudden vision changes and, without proper treatment, may lead to serious complications that affect your sight.

Table of contents

• What is retinal vein occlusion?
• Types of retinal vein occlusion
• How common is this condition?
• Symptoms
• Causes and how it develops
• Risk factors
• Possible complications
• How doctors diagnose retinal vein occlusion
• Treatment options
• Outlook and recovery
• Prevention

What is retinal vein occlusion?

Retinal vein occlusion is a partial or total blockage in a vein that drains blood from your retina, the layer of tissue at the back of your eye that helps translate light into images you can see^[1]. Your retina needs blood flow like all organs in the body. Arteries bring blood into the retina, and veins take the blood back out^[2].

When a retinal vein becomes blocked, blood cannot leave your retina properly. This can lead to complications, including raised pressure in your eye and swelling. These issues need prompt treatment to prevent or minimize vision loss^[1].

There is currently no safe way to unblock the vein itself. However, treatment can manage complications and protect your vision. Eye care specialists tailor treatment to your individual needs^[1].

Types of retinal vein occlusion

There are two main types of retinal vein occlusion, depending on where the blockage occurs^[1].

Central retinal vein occlusion (CRVO) occurs when the main vein that drains blood from the retina becomes blocked. This blockage happens behind the lamina cribrosa, which is a part of the optic nerve at the back of the eye^[6]. Central retinal vein occlusion can cause significant vision loss and is often associated with other health problems^[4].

Branch retinal vein occlusion (BRVO) happens when one of the smaller branch veins of the retina becomes blocked. This type usually affects a smaller area of the retina and may result in less severe vision impairment. Branch retinal vein occlusion is more common than the central type^[1][4].

Central retinal vein occlusion is further divided into two categories: non-ischemic (also called perfused) and ischemic (also called nonperfused). Non-ischemic CRVO is the most common form, accounting for about 70% of cases. People with this type often have better vision, typically better than 20/200. Ischemic CRVO accounts for about 30% of cases and has a much lower visual outlook, with around 90% of patients having visual acuity worse than 20/200^[6].

How common is this condition?

Retinal vein occlusion is the second most common disorder affecting your retina. The most common retinal condition is diabetes-related retinopathy^[1][2].

Researchers estimate that globally, retinal vein occlusion affects over 16 million people. Central retinal vein occlusion affects between 1 and 4 in 1,000 people, while branch retinal vein occlusion affects between 6 and 12 in 1,000 people^[1].

Symptoms

Symptoms of retinal vein occlusion typically affect one eye. The condition usually develops suddenly or over a period of hours or days^[1][7].

Common symptoms include blurry vision or vision loss, which may start suddenly or develop gradually. You may also see floaters, which are dark spots or lines that seem to float in your field of vision^[1]. Some people experience distorted or wavy vision^[4].

In more severe cases, you might feel pain or pressure in your eye^[1]. Some people have difficulty seeing in low light conditions or notice missing areas in their field of vision^[4].

You may not have any symptoms until complications arise. Some people don’t realize there’s a problem until their provider finds the issue during a routine eye exam^[1].

Causes and how it develops

Retinal vein occlusion is most often caused by hardening of the arteries, called atherosclerosis, and the formation of a blood clot^[5].

A disruption to normal blood flow through your retinal vein causes this condition. The disruption may happen due to a blood clot, a slowdown of blood flow, or compression of your retinal vein^[1].

The retinal artery and vein share a common outer covering. Changes in the arterial wall associated with atherosclerosis or high blood pressure can make the artery stiff. This stiffness can cause the artery to press on the retinal vein at points where they cross over each other. This pressure can damage the inner lining of your retinal vein, creating conditions where a blood clot is more likely to form^[1][5][7].

Risk factors

Being over age 40 is a major risk factor. Retinal vein occlusion usually affects people in their 50s or 60s. A primary risk factor for the development of this condition is age, with 90% of patients older than 50 years old^[1][6].

Having certain medical conditions can also raise your risk. These include high blood pressure, atherosclerosis, diabetes, and glaucoma^[1][4][5][6].

Other risk factors include high cholesterol, smoking, and certain blood clotting disorders^[4][6]. Prior history of retinal vein occlusion in one eye raises your risk of developing the condition in your other eye^[1].

Possible complications

Retinal vein occlusion can lead to several complications that may cause further vision problems^[1].

Cystoid macular edema is swelling in the center of your retina, called the macula. This swelling happens when fluid leaks from blocked blood vessels. It can cause blurry vision or loss of vision and is the most common treatable cause of decreased visual acuity in patients with retinal vein occlusion^[1][5].

Neovascularization of the eye occurs when abnormal blood vessels form in different parts of your eye, typically your iris (the colored part of your eye). This condition is called rubeosis iridis and happens in about 1 in 4 people with retinal vein occlusion. These abnormal new blood vessels can grow because the retina doesn’t get enough blood flow and releases a protein called vascular endothelial growth factor (VEGF)^[1][7].

Glaucoma can develop when abnormal blood vessels grow in the front part of the eye, causing high pressure inside the eye. This is called neovascular glaucoma and can lead to pain and vision loss^[5][10].

How doctors diagnose retinal vein occlusion

Eye doctors can check for retinal vein occlusion as part of a comprehensive dilated eye exam. The exam is simple and painless. Your doctor will give you some eye drops to dilate (widen) your pupil and then check your eyes for retinal vein occlusion and other eye problems^[12].

Other tests your doctor may use include^[5][12]:

• Exam of the retina after dilating the pupil
• Fluorescein angiography, where your eye doctor injects a special dye into your arm that travels to your eye. The doctor then uses a camera to take photos of the retinal veins as the dye moves through them
• Optical coherence tomography (OCT), where your eye doctor takes pictures of your retina with a special machine. This can help your doctor see how much swelling there is
• Tests to measure pressure inside your eye
• Visual acuity test to determine the smallest letters you can read on a chart
• Testing of side vision (visual field examination)

Your doctor may also recommend blood tests to check for diabetes, high cholesterol, and triglyceride levels. In people under age 40, blood tests may look for clotting or blood thickening problems^[5].

Treatment options

There is no cure for retinal vein occlusion, and there is no way to reverse or open the blockage. However, treatment can improve your vision or keep your symptoms from getting worse^[5][12].

Many people will regain vision, even without treatment. However, vision rarely returns to normal. Approximately half of non-ischemic cases resolve without treatment or intervention^[5][6].

Treatment for the complications of retinal vein occlusion may include^[5][10][12]:

• Intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) drugs into the eye. These medications are delivered directly into the eye to reduce swelling and improve blood flow in the retina. They may block the growth of new blood vessels that can cause glaucoma
• Intravitreal injection of corticosteroids, including triamcinolone acetonide or dexamethasone implants, which work by reducing inflammation and decreasing swelling
• Laser treatment, which may be used to target areas of the retina with abnormal blood vessels or swelling, or to prevent the growth of new abnormal blood vessels that lead to glaucoma

It’s important to manage underlying conditions such as diabetes, high blood pressure, and high cholesterol levels. Some people may need to take aspirin or other blood thinners to help prevent another blockage from forming in the same or the other eye^[5][10].

The health care provider will closely monitor any blockage for several months. Some harmful effects, such as glaucoma, may take 3 or more months to develop after the occlusion^[5].

Outlook and recovery

The outcome varies. People with retinal vein occlusion often regain useful vision^[5].

It is important to properly manage conditions such as macular edema and glaucoma. However, having either of these complications is more likely to lead to a poor outcome^[5].

Recovering from retinal vein occlusion treatment may take time, and it’s important to attend all follow-up appointments to monitor your progress. Your doctor will work closely with you to manage any underlying health conditions and help you regain the best possible vision^[4].

Prevention

Retinal vein occlusion is a sign of a general blood vessel disease. Measures used to prevent other blood vessel diseases may decrease the risk for retinal vein occlusion^[5][10].

These measures include:

• Eating a low-fat diet
• Getting regular exercise
• Maintaining an ideal weight
• Not smoking
• Controlling diabetes, high blood pressure, and high cholesterol levels

Aspirin or other blood thinners may help prevent blockages in the other eye. Controlling diabetes may help prevent retinal vein occlusion^[5][10].

• Retina
• Retinal veins
• Macula
• Optic nerve
• Iris