A retinal vein occlusion occurs when a vein in the retinal circulation has become blocked. Retinal veins carry blood from the retina back to the heart for re-circulation. If one of these veins becomes blocked a pressure build up causes leakage of blood and fluid in the retina. This blockage can cause hemorrhages, lack of oxygen and swelling of the retina.
There are two types of retinal vein occlusions:
- Central Retinal Vein Occlusion (CRVO) - Occurs when the main retinal vein is blocked. This results in poor blood flow throughout the entire retina and can cause severe visual loss, particularly in older people.
- Branch Retinal Vein Occlusion (BRVO) - Occurs when a smaller branch of the main retinal vein is blocked. This results in damage to the area of the retina drained by this branch. Visual loss varies but is not as severe as with a central retinal vein occlusion.
Who is at Risk:
Retinal vein occlusions are more common in people with:
- High blood pressure
- Age-related vascular disease
- Blood disorders
What are the Symptoms:
Blurred vision is the main symptom of a retinal vein occlusion. This occurs when the excess fluid leaking from the blocked vein collects at the macula (the area of the retina responsible for central vision).
Floaters can be another sign of a retinal vein occlusion. They appear as 'spots' which float through the visual field. When an area of the retina is not working properly abnormal blood vessels may grow (neovascularisation). These abnormal blood vessels are fragile and can cause bleeding or leakage of fluid into the vitreous (gel-like fluid which fills the eye). Floaters may be noted when this occurs.
Pain in the eye can occur as a complication of a central retinal vein occlusion. This is caused by excessive eye pressure called neovascular glaucoma.
How is it Diagnosed:
Your ophthalmologist may perform fluorescein angiography to diagnose and monitor your retinal vein occlusion. Fluorescein angiography involves intravenous administration of a diagnostic dye called fluorescein. As the dye circulates through the retinal blood vessels a series of photographs are taken. The test is performed to highlight the occlusion as well as areas of swelling and assess the amount of accumulated fluid.
OCT is also performed to measure macular edema (swelling). Additionally blood tests could also be ordered to determine the cause of the occlusion.
What are the treatment options:
Your Ophthalmologist will discuss the different treatment options available. Treatments may include lifestyle and dietary modification, laser treatment, antihypertensive medication, and intravitreal injections of anti-VEGF or steroids.