Central Retinal Vein Occlusion

A central retinal vein occlusion is a blockage of the main retinal vein that drains blood from the eye. This blockage is caused by compression of the vein in the lamina cribrosa, a small area shared with the central retinal artery, where the vein leaves the eye.

Classic presentation of Central Retinal Vein Occlusion Note the widely dilated retinal veins (the thick, dark red lines) which are also twisted and snake-like (called tortuous).  This is a result of built up pressure from bloodflow that cannot exit the eye freely..

If certain processes cause a shrinkage of space in this area - such as from arteriosclerotic changes (hardening) in the artery, glaucoma, inflammation of the optic nerve or changes in blood flow - the central retinal vein can become compressed leading to a blockage. The blockage causes a build-up of pressure within the vein resulting in haemorrhaging and leakage of fluid.

In all cases, the blockage will resolve as the eye begins to form bypass channels for blood to drain out of the eye.
 

Main complications include:
 

Macula Oedema
The leakage and bleeding causes the macula to swell leading to blurred vision.

Ischemia
A lack of blood supply and oxygen to the retina Neovascularisation In severe cases of ischemia, neovascularisation can occur where new, abnormal vessels may begin to grow. These abnormal blood vessels may grow throughout the eye where they can burst and bleed and cause severe visual loss.

Frequently Asked Questions

What are the symptoms of CRVO?

Symptoms may include:

• Sudden loss of vision – the loss of vision may range from partial to complete.
• Black spots appearing in your vision.
• Painful blind eye.

What are the risk factors?

You may be at risk if you have any of the following:

• Hypertension (high blood pressure)
• Glaucoma
• Diabetes
• Hypercholesterolaemia (high cholesterol)
• Smoking

What treatments are available?

1. Laser Photocoagulation
   If you have retinal ischaemia, large areas of the retina are treated by laser. The aim is to prevent abnormal blood vessels from growing and the resulting visual loss.
    
2. Injections with Avastin
   Avastin is a type of drug that is given via an intravitreal injection (injection into the vitreous of the eye). This drug both used to stop the factors responsible for the growth of new blood vessels in the eye and also to reduce the swelling of the macula. Repeat injections are often required with around 6 weeks between injections.

Are there any preventative measures I can take?

• Keep your blood pressure in the normal range and take blood pressure lowering medication if required.
• Reduce your intake of saturated fats
• Reduce your intake of salts