Retinal vascular occlusion (RVO) occurs when small veins in the back of the eye become blocked, and blood cannot flow through them. The condition can affect vision but does not cause total blindness.

Doctors use the terms “retinal vascular occlusion” and “retinal vein occlusion” to refer to the same condition. RVO happens when tiny veins in the retina become blocked, typically by a blood clot, preventing the passage of fresh blood. This can cause sudden, painless vision loss.

The prevalence of RVO increases with age, mainly affecting older adults ages 60–70 years old. RVO affects 0.77% of the global population ages 30 years and older.

This article examines the types of RVO, diagnosis and treatment, complications, prevention, and outlook.

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The retina is the layer of cells lining the back wall of the eye. Light focuses on the retina, which sends signals through the optic nerve to the brain.

The retina contains both veins and arteries. Arteries carry oxygenated blood from the heart and lungs throughout the body. Veins return blood used by cells back to the heart and lungs. Retinas require a continual blood supply.

Blood clots can form in veins or, less commonly, arteries. They can prevent blood from passing through. When this happens in a retinal vein, doctors call it RVO.

The blockage causes blood to back up in the vein, where it can cause swelling. Blood may also leak into the rest of the eye, damaging the retina.

Learn about the anatomy of the eye.

Doctors have identified two types of RVO:

Sudden vision loss in one eye is the predominant symptom of RVO. A person may lose all of the vision in the eye due to CRVO or part of it due to BRVO. The condition is painless.

Other symptoms include:

  • loss of side or peripheral vision
  • distorted vision
  • blind spots

Learn about causes of blurry vision in one eye.

To diagnose RVO, a doctor will examine the eye and run a series of tests. They will establish whether a blood clot exists and then investigate why an individual might be susceptible to blood clots.

Tests they may perform include:

  • fluorescein angiography, which involves injecting dye into the arm and taking photos of the retina to observe how the dye circulates
  • intraocular pressure, which measures the pressure inside the eye
  • checking how the pupil responds to light
  • taking photos of the retina
  • optical coherence tomography, which uses light waves to create images of the eye
  • a slit lamp exam, which allows an ophthalmologist to examine the eye’s structures
  • a visual field exam, which tests side vision
  • visual acuity using an eye chart, which tests sharpness of vision

RVO may cause the eye’s macula to swell, worsening vision. The goal of treatment is to slow or stop the leakage of blood and fluid into the eye and preserve vision. The doctor may recommend one or more of several treatment options.

Some people may benefit from medication injections into the eye. A medication called anti-VEGF works to decrease swelling in the macula.

If anti-VEGF therapy does not work, a doctor might recommend steroid injections or a steroid implant.

A type of laser surgery called focal laser treatment might help stop fluid from leaking into the eye. During this procedure, a doctor uses a laser to burn small vessels near the macula. This helps prevent them from leaking blood.

Vision disturbances are the main complication of RVO. However, the brain adjusts in time, and the healthy eye becomes dominant. The brain learns to ignore input from the affected eye and take in information from the unaffected one.

During this adjustment period, determining distances or feeling balanced may be difficult. A person may also have difficulties with depth perception.

Inside the eye, additional complications can develop, including:

  • Macular edema: Blood leakage into the macula causes swelling, known as macular edema.
  • Vitreous hemorrhage: This is the presence of blood in the vitreous portion (clear part) of the eye.
  • Neovascular glaucoma: This is the growth of new, often leaky, blood vessels, sometimes in the wrong part of the eye.

RVO usually results from an underlying condition that causes blood to clot. A 2023 literature review discusses strong evidence that cardiovascular diseases are the most common risk factor for RVO.

Managing the following conditions can help reduce the risk of RVO:

People can work with a doctor to manage these conditions. They may also adopt the following lifestyle measures:

The outlook for RVO is better in younger people. In older adults, one-third of cases improve without treatment, one-third stay the same, and one-third worsen. Recovery often depends on a person’s visual acuity before the RVO.

An ophthalmologist typically leads the medical care of someone with RVO. However, other specialists may contribute, depending on the underlying cause of the blockage.

RVO occurs when there is a blockage in a small vein in the retina. Pressure builds up, and blood and fluid can leak into the eye, damaging the macula and affecting vision.

The main symptom is sudden, painless vision loss in one eye, affecting either central or peripheral vision.

A doctor may recommend regular anti-VEGF or steroid injections into the eye to preserve vision. Laser surgery may also be an option.