Retinal vein occlusion is a condition in which one of the veins carrying blood away from the retina becomes blocked. The retina is the light-sensitive layer at the back of the eye that allows us to see.
A retinal vein occlusion can affect the main retinal vein, known as a central retinal vein occlusion (CRVO), or one of its smaller branches, known as a branch retinal vein occlusion (BRVO).
The effect on vision varies considerably. Some people experience relatively mild changes, while others develop significant blurred or reduced vision, particularly when the central part of the retina, the macula, becomes swollen.
At The Retina Clinic London, we use detailed retinal examination and advanced imaging to establish the extent of the condition, identify any complications and determine the most appropriate monitoring or treatment pathway.
What are the symptoms of retinal vein occlusion?
Symptoms can vary depending on which vein is affected and the extent of the retinal changes.
They may include:
- Sudden or noticeable blurring of vision in one eye
- Reduced central vision
- Distorted vision
- A dark or blurred area within the field of vision
- Changes in visual clarity that develop over hours or days
Retinal vein occlusion is usually painless.
Any new or sudden change in vision should be assessed promptly by an eye specialist.
What causes retinal vein occlusion?
A retinal vein occlusion occurs when blood flow through a retinal vein becomes obstructed.
Several general health and eye-related factors can be associated with an increased risk of retinal vein occlusion. These include:
- High blood pressure
- Raised cholesterol
- Diabetes
- Glaucoma or raised pressure within the eye
- Increasing age
- Other cardiovascular risk factors
In some patients, particularly younger people or those with an unusual presentation, further medical investigation may be appropriate.
Assessment therefore considers not only the eye itself, but also whether relevant general health factors should be reviewed with the patient’s GP or other medical specialists.
Types of retinal vein occlusion
Branch Retinal Vein Occlusion (BRVO)
A branch retinal vein occlusion occurs when one of the smaller veins draining part of the retina becomes blocked.
The effects are usually confined to the area of retina served by that vein. If the macula is affected, fluid can accumulate within the retina and reduce or distort central vision.
Central Retinal Vein Occlusion (CRVO)
A central retinal vein occlusion affects the main vein responsible for draining blood from the retina.
CRVO can cause more widespread retinal changes and requires careful assessment and monitoring. In some cases, reduced retinal circulation can increase the risk of abnormal new blood vessels developing, making ongoing follow-up particularly important.
How we diagnose retinal vein occlusion
At The Retina Clinic London, diagnosis begins with a detailed specialist retinal examination.
Depending on the findings, assessment may include:
Optical Coherence Tomography (OCT)
OCT provides highly detailed cross-sectional images of the retina. It is particularly important for detecting and measuring macular oedema, which is swelling caused by fluid accumulating within the central retina.
OCT can also be repeated during follow-up to monitor changes and assess the response to treatment.
OCT Angiography
OCT angiography is a non-invasive imaging technique that allows our specialists to examine the retinal circulation without injecting a dye.
It can provide additional information about areas where retinal blood flow has been affected.
Fluorescein Angiography
Fluorescein angiography uses a fluorescent dye to examine the retinal circulation in greater detail.
Where required, it can help identify areas of leakage, reduced circulation or abnormal blood vessel growth and assist with treatment planning.
Ultra-widefield retinal imaging
Ultra-widefield imaging allows a large area of the retina to be documented in a single image. This can be particularly valuable when changes extend beyond the central retina.
The results of these investigations are interpreted alongside the clinical examination to build a detailed picture of how the retinal vein occlusion is affecting the eye.
Macular oedema and retinal vein occlusion
Macular oedema is one of the most important causes of reduced vision following retinal vein occlusion.
The macula is responsible for detailed central vision. When a retinal vein becomes blocked, fluid can leak from affected blood vessels and accumulate within the macula.
This swelling can cause blurred, distorted or reduced central vision.
High-resolution OCT allows us to measure this fluid precisely and monitor how it changes over time.
How is retinal vein occlusion treated?
Treatment depends on the type of retinal vein occlusion, its effect on the retina and whether complications such as macular oedema or abnormal new blood vessel growth have developed.
Treatment is directed at managing these complications rather than physically removing the original vein blockage.
Intravitreal injections
Intravitreal injections deliver medication into the vitreous, the clear gel inside the eye.
Anti-VEGF medicines are commonly used to treat macular oedema associated with retinal vein occlusion. VEGF, or vascular endothelial growth factor, is a naturally occurring protein that can contribute to blood vessel leakage and abnormal blood vessel growth.
By reducing its activity, anti-VEGF treatment can reduce retinal swelling and help protect or improve vision in appropriate patients.
Steroid treatment may also be considered in selected cases.
Treatment is tailored according to the retinal findings, visual function and response seen on follow-up imaging.
Retinal laser treatment
Laser treatment has specific roles in retinal vein occlusion and is not required for every patient.
It may be considered in selected cases, particularly where abnormal new blood vessels develop or for certain complications associated with branch retinal vein occlusion.
Our specialists will advise whether laser has a role after detailed imaging and examination.
Monitoring retinal vein occlusion
Careful follow-up is an important part of managing RVO.
Even when immediate treatment is not required, monitoring may be recommended to look for:
- Macular oedema
- Changes in retinal circulation
- Abnormal new blood vessel growth
- Changes in vision
- The response to any treatment already given
The frequency and type of follow-up will depend on the individual retinal findings.
Looking beyond the eye
Retinal vein occlusion can be associated with wider cardiovascular and metabolic risk factors.
Where appropriate, patients may be advised to have factors such as blood pressure, blood glucose and cholesterol reviewed by their GP or relevant medical specialist.
This forms an important part of the overall approach to retinal vascular health.
A specialist approach to retinal vein occlusion
Retinal vein occlusion can affect each patient differently, so careful assessment is important in understanding how much of the retina has been affected and whether complications such as macular oedema or abnormal new blood vessels have developed.
At The Retina Clinic London, your consultant brings together the findings from your retinal examination and advanced imaging to build a detailed picture of the condition. This allows us to distinguish changes that require treatment from those that may be monitored safely over time.
Where treatment is appropriate, this may include intravitreal injections or retinal laser, depending on the clinical findings. Follow-up imaging is then used to monitor the retina closely and assess how it is responding.
As an active clinical research centre, The Retina Clinic London is also involved in the development and evaluation of new retinal treatments. Where a relevant clinical trial is available, suitable patients may be invited to discuss participation. Eligibility is assessed individually, and taking part is always voluntary.
Our aim is to give every patient a clear understanding of what has happened, what it means for their vision, and what the next steps should be.
If you have experienced a new or sudden change in vision, specialist assessment can help establish the cause and whether treatment or monitoring is required.
To book your consultation, please call us on +44 (0)20 4548 5310.
We’ll be glad to guide you through the next steps.