Retinal Vein Occlusion 

The eye has a lens in front that focuses images inside the back of the eye (on the retina). The light that passes through the lens focuses on the retina to help interpret images. The retina has special nerve cells that convert the light into signals transported to the brain through the optic nerve for image interpretation. Any condition that affects the retina can impair vision. 

Arteries in the body transport blood from the heart to other body parts, while the vein transports blood from different body parts back to the eye. When the veins or arteries get blocked, an occlusion or even stroke can occur.  

Obstruction of blood flow can happen in arteries(supply blood) due to clot formation or in veins(drainage) due to a thickening of blood vessels as a result of blood vessel disease which can also happens in the retinal blood vessels.

The nerve cells in the retina need continuous blood supply from the blood vessels to provide the retina with nutrients and oxygen. 

For a stroke to occur, a small blood clot will block blood flow through an artery in the brain, preventing the area from getting blood which causes damage. 

This damage can occur in any body part. When the veins in the retina get blocked, it stops draining blood from the retina. The result is haemorrhage or bleeding and fluid leakage from the blocked vessels. Called RVO

Two types of retinal vein occlusion affect people. They include:

• Central retinal vein occlusion (CRVO)

This occurs from a blockage in the main retinal vein.

• Branch retinal vein occlusion (BRVO)

This condition occurs due to blockage in one of the smaller retinal veins branches.

How does RVO cause reduce/ loss of vision?

• Macular oedema 

The macula is the small, middle part of the retina that gives sharp, detailed vision, including reading vision. If fluid and blood leak into the macular, it may cause swelling, leading to a condition known as macular oedema. Macular oedema can cause blurred vision or vision loss.  

• Neovascularisation 

RVO may cause lack of oxygen supply of tissue and the development of new, abnormal retinal blood vessels, leading to a condition known as neovascularisation. The new blood vessels are prone to blood and fluid leakage into the vitreous. 

The vitreous is a clear, jelly-like substance inside the eye. Blood and fluid in the vitreous will cause clouds or small spots called floaters in your field of vision. People with severe neovascularisaton may experience retinal detachment in the back of their eyed to traction of this tissue. 

• Neovascular glaucoma 

The new blood vessels in some parts of the eye can result in pain and increased eye pressure. 

• Blindness 

Blindness can occur from RVO, particularly if the condition is left untreated and progress. 

Causes of RVO

RVO occurs when renal vein get blocked. In some  cases, it occurs because veins in the eyes are narrow. Retinal vein occlusion usually affects people with high cholesterol levels, high blood pressure, diabetes, and other medical conditions affecting blood vessels. 

RVO symptoms 

Symptoms of RVO range from mild to severe. Some people experience blurred vision, and vision loss may occur. The condition usually affects only one eye. Blurring or vision loss may be mild in the initial stages but worsens over hours or days. In some cases, complete vision loss occurs almost immediately. 

If you experience these symptoms, ensure you contact your eye doctor to schedule an urgent appointment. RVO can permanently damage the retina and cause irreversible vision loss and other eye problems if left untreated. 

RVO diagnosis 

The doctor may use the following to diagnose retinal vein occlusion. 

• Optical Coherence Tomography (OCT)

This test gives high-definition images of the retina using a scanning ophthalmoscope with a high resolution. The doctor can use these images to check for oedema and swelling by measuring the retina’s thickness. The images from OCT can determine the progress of the condition during treatment. Modern version of OCT available to Optimal Vision surgeons called OCT angio can investigate your retina blood vessels with advance technology without injection of dye.

• Ophthalmoscopy

The doctor can see the changes in your retina by examining it with slit lamp(eye microscope) and ophthalmoscope. 

• Fluorescein angiography 

In the fluorescein angiography procedure, the doctor will inject a dye into a vein in your arm. The dye will travel to the retinal blood vessels, allowing the doctor to take images of the blood vessels. 

RVO treatment 

There are many advance treatment available for RVO and many benefit from close to normal recovery if diagnosed and treated early, About one in three persons have improved vision; the condition may remains the same in others, while others notice a gradual improvement in vision. However, it may take about a year or longer to see the final result. 

In certain cases, the blocked blood vessels will cause a build-up of fluid in the retina, like a sponge absorbing water. It may lead to the formation of new blood vessels. 

Common treatments for RVO include:

• Intravitreal injection of anti-vascular endothelial growth factor (VEGF) medications 

These medications target VEGF. This is a vital growth factor that leads to macular oedema. Injection of Eylea and Lucentis are some examples.

• Intravitreal injection of corticosteroid drugs 

These medications treat the factors that cause oedema. A popular treatment is injection of Azurdex (dexamethasone steroid implants)

• Focal laser therapy 

Focal laser therapy uses lasers on swollen areas to reduce oedema.

• Pan-retinal photocoagulation therapy 

This treatment aid to avoid the formation of new blood vessels when retinal vein occlusion occurs.  

You will need follow-up visits to monitor the progress of the disease. Detecting changes in the condition is necessary to aid in formulating treatment plans. Ensure you also inform your GP if you have retinal vein occlusion to ensure evaluation and treatment of any underlying chronic condition.  

If you experience a sudden change in your vision, feel free to visit Optional Vision or call 020 7183 3725 to book an eye doctor appointment. Our doctor will conduct the necessary tests to determine if you have retinal vein occlusion and offer the right treatment.