Understanding retinal vein occlusion

Retinal vein occlusion (RVO) is a condition that affects the small veins that drain blood away from the retina, the light-sensitive layer at the back of the eye that plays a big part in our ability to see. When one of these veins becomes blocked, it can lead to sudden changes in vision and, in some cases, long-term sight problems if not managed effectively. In this article, a consultant ophthalmic surgeon explains the dangers of retinal vein occlusions, and how they can be managed.

Who is at risk of retinal vein occlusion?

RVO tends to occur more frequently in people over the age of 50, though it can affect younger individuals with certain underlying risk factors. The blockage is usually caused by a blood clot or compression of the vein, leading to poor circulation in the retina.

Risk factors include:

High blood pressure
Diabetes
High cholesterol
Smoking
Glaucoma
Certain blood disorders or clotting abnormalities

There are two main types of RVO:

Central retinal vein occlusion (CRVO), where the main vein at the back of the eye is blocked
Branch retinal vein occlusion (BRVO), where one of the smaller branches of the central vein is affected

Both types can cause vision problems, but CRVO is generally more severe.

Recognising the symptoms and possible complications

RVO often presents with sudden, painless vision loss or blurring in one eye. In BRVO, vision loss may be partial and affect only part of the visual field, while CRVO typically causes more widespread visual disturbance.

Symptoms may include:

Blurred or distorted vision
Dark patches or floaters
Sudden loss of central or peripheral vision

In some cases, vision may improve over time, but complications can occur, such as:

Macular oedema (swelling in the central part of the retina, leading to blurred central vision)
Neovascularisation (abnormal blood vessel growth, which can lead to bleeding, glaucoma, or retinal detachment)
Permanent vision loss (especially if treatment is delayed or complications arise)

How is retinal vein occlusion diagnosed?

Diagnosis usually begins with a comprehensive eye examination, including checking visual acuity and the pressure inside the eye. An ophthalmologist will also examine the retina using a technique called fundoscopy, which allows direct visualisation of the blood vessels.

Further tests may include:

Optical coherence tomography (OCT) to assess retinal thickness and detect swelling
Fluorescein angiography, where a dye is injected into a vein in the arm to highlight blood flow in the retina
Blood tests and blood pressure monitoring to look for underlying causes such as diabetes or clotting disorders

Early diagnosis is key to reducing the risk of permanent vision loss and starting the right treatment as soon as possible.

How is retinal vein occlusion treated?

While there is no cure for RVO, there are effective treatments to manage the condition and reduce the risk of complications. This can include:

Intravitreal injections of anti-VEGF medications (such as aflibercept or ranibizumab) are the most common treatment for macular oedema. These are given directly into the eye and help reduce swelling and improve vision.
Steroid injections or implants may be used in some cases, particularly if anti-VEGF treatment is not suitable or effective.
Laser treatment may be used to reduce the risk of abnormal blood vessel growth and bleeding in some patients.
Managing underlying conditions, such as controlling blood pressure, cholesterol and diabetes, is essential to prevent further damage and protect the other eye.

Treatment is usually given over several months, with regular monitoring through follow-up visits and scans.

Can retinal vein occlusion be prevented?

While RVO cannot always be prevented, the risk can be reduced by taking steps to improve general vascular health:

Keep blood pressure and diabetes under control
Stop smoking, as this significantly increases the risk of vascular problems
Exercise regularly and maintain a healthy weight
Attend regular eye tests, especially if you have known risk factors

Patients who have had RVO in one eye are at higher risk of developing it in the other, so regular monitoring and risk factor management are especially important.