Retinal Vein Occlusion
What is a retinal vein occlusion?
A retinal vein occlusion means that a vein in the retina of the eye has become blocked. The retina is the light-sensing tissue at the back of the eye. The veins drain blood out of the retina and return it to the heart.
Blockage or occlusion in the vein prevents adequate blood flow in the affected area. The walls of the vein leak blood and excess fluid into the retina.
What are the types of retinal vein occlusion?
There are two types of retinal vein occlusions:
- Central retinal vein occlusion (CRVO)
- Branch retinal vein occlusion (BRVO)
With a central retinal vein occlusion, the main retinal vein is blocked. Blood flow is poor throughout the entire retina. The amount of visual loss varies, but is often severe in older people.
With a branch retinal vein occlusion, a small branch of the main retinal vein is blocked. Only the part of the retina drained by this branch vein is damaged. Vision loss varies with this type of occlusion as well, but is not as severe as with a CRVO.
Who is at risk for a retinal vein occlusion?
These are more common in people who have:
- Glaucoma (abnormal eye pressure)
- Age-related vascular (blood vessel) disease
- High blood pressure
- Blood disorders
What are the symptoms of a retinal vein occlusion?
Blurred vision is the main symptom of a retinal vein occlusion. This occurs when the excess fluid leaking from the vein collects in the macula. The macula is the central area of the retina which is responsible for our central detailed vision. If the macula swells (macular edema) with excess fluid, vision blurs.
Floaters can appear as spots which interfere with vision. When retinal blood vessels are not working properly, the retina may grow abnormal blood vessels (neovascularization), and they are fragile. These can bleed or leak into the vitreous (the gel-like fluid that fills the center of the eye) and cause the floaters.
Pain in the eye sometimes occurs as a complication of a severe CRVO. It is caused by excessive eye pressure, called neovascular glaucoma.
What tests might the doctor order?
After a complete eye examination, your ophthalmologist may order blood tests and/or a test of the retinal circulation called a fluorescein angiogram. A dye (fluorescein) is injected into your arm and then special photos are taken of the inside of your eye when the dye passes through the blood vessels. Your ophthalmologist may also suggest a visit to your family physician to discover and manage any associated medical problems (diabetes, vascular disease, high blood pressure, etc.).
What treatment is available?
There is no cure for a retinal vein occlusion. Your ophthalmologist may recommend a period of observation, since hemorrhages and excess fluid may subside on their own. According to the Branch Retinal Vein Occlusion Study (BRVOS), 50% of patients with branch retinal vein occlusions showed spontaneous improvement.
Laser surgery improves sight in some patients with BRVO and macular edema. Again, according to the BRVO Study, after a four month observation period, patients with a BVO generally had benefited from laser treatment if they showed good macular circulation on a fluorescein angiogram as well as associated macular edema, but their vision did not usually return to normal. Patients with CRVO and macular edema are not helped by laser surgery.
Laser surgery is very effective in preventing vitreous hemorrhage and neovascular glaucoma. However, it does not remove hemorrhage or cure neovascular glaucoma once they are already present. It is best to treat people at risk for these complications before they occur.
Your ophthalmologist will decide whether laser surgery is appropriate for you. Frequent follow-up examinations are essential. You should also make sure any associated medical condition is treated by your regular physician.