While we have all heard of eye conditions like cataracts and glaucoma, one that often escapes attention is retinal vein occlusion. Despite its relative obscurity, it is one of the leading causes of sudden painless loss of sight. Mr Praveen Patel, leading London ophthalmologist, explains:
What is retinal vein occlusion?
Retinal vein occlusion (RVO) is when the small veins that carry blood away from the retina (the light-sensitive layer at the back of the eye) become blocked. The blockage forces blood and other fluids to drain into the retina, causing bleeding and swelling of the retina (macular oedema). Blockage also a lack of oxygen in the retina (hypoxia). This affects the ability of the retinal cells to receive light and send signals to the brain to create a visual image. Vision tends to become blurry as a result.
Retinal vein occlusion – quick facts:
- RVO is the second most common retinal vascular disorder (after diabetic retinopathy)
- RVO is one of the most common causes of sudden painless loss of vision
- It can occur at any age, but most commonly after 60
- There are two types:
- Branch retinal vein occlusion – blockage of one of the four smaller retinal veins which feed into the larger central retinal vein.
- Central retinal vein occlusion – blockage of the large central vein.
Retinal vein occlusion is thought to be caused by atherosclerosis (hardening of blood vessel walls) of closely associated retinal arteries and/or the formation of a blood clot blocking the small veins that carry blood away from the eye. Various things can influence the development of RVO:
- Hypertension (high blood pressure)
- High cholesterol
- Certain rare blood disorders
- Other eye conditions, e.g. certain types of uveitis.
Can retinal vein occlusion be cured?
While many patients regain vision, it rarely fully recovers, as it is usually impossible to remove the blockage. Treatment is focussed on preventing further bleeding and further RVOs, by managing diabetes, blood pressure and cholesterol levels. It’s also important to carry out blood tests to rule out other causes of RVO.
One of the main ways RVO causes vision loss is through the development of macular oedema (sponge-like thickening or swelling of the retina). Thankfully, there are effective treatments for macular oedema caused by RVO. These treatments are given by eye injections using a local anaesthetic and need to be given on a repeated basis to get the best results. Early treatment of macular oedema is also key as this leads to better improvements in vision.
If you experience vision loss or blurring in part of all of one of your eyes, it is essential to consult your doctor or a specialist.