Central retinal vein occlusion occurs when the blood supply to the retina is blocked. The retina is the membrane located at the back of the eye.
The retina houses a main artery and a main vein. Veins and arteries carry blood throughout the body including the eyes. When the main vein in the eye is blocked, blood and other fluids spill into the retina. The fluid then collects in the macula (a part of the retina that gives the eye its central vision) causing it to swell (macular edema).
The swelling then affects an individual’s central vision. This disruption can rapidly cause the death of nerve cells in the eye leading to loss of vision. CRVO always happens in one eye.
Also Known As
Non-ischemic CRVO - Less serious, accounting for 75% of all cases and with a better prognosis.
Ischemic CRVO - More serious and can lead to loss of vision.
Intermediate or indeterminate because they are neither clearly ischemic or non-ischemic
Causes and Risk Factors
Sometimes the underlying cause of CRVO is unknown. CRVO mainly occurs when the main vein that takes blood away from the retina is blocked. The blockage may happen in the main vein or branches of the vein located in the retina. Disease can also cause the artery walls to narrow down leading to CRVO.
Older people from age 50 and above are at risk of developing CRVO. Other risk factors may include hypertension, diabetes, glaucoma and increased blood viscosity.
Signs & Symptoms
The symptoms of CRVO may include:
- Sudden loss of vision in one eye either partly or fully
- Blurry vision, partly or wholly in one eye
- Floaters (spots on the eye)
- Pain and pressure in the affected eye in severe cases
- Abnormal blood cells growing on the retina or iris. These growths may bleed or cause a painful kind of glaucoma
The eye professional will conduct a thorough examination of the eye. The procedures or examinations may include:
- Dilating the eye using eye drops
- Fluorescein angiography to check how damaged the retina is - The professional will inject dye into a vein in the arm and photograph the retina
- Optical coherence tomography (imaging) to check if the retina is swollen
- Use of an ophthalmoscope to see the changes in the blood vessels and the retina
- Further tests to reveal disorders that may increase the risk of the blockages - These disorders include diabetes, hypertension and so on
Treatment of CRVO-related complications is aimed at reducing macular edema.
Some patients may regain vision without medical attention.
There is no treatment for CRVO (the vein cannot be unblocked). However, there are treatments related to CRVO. It’s important to determine the cause of the blockage and treat accordingly. Any leaking blood vessels should be sealed.
Injections (VEGF blockers) and steroids are used to reduce the swelling in the macular edema. Eye drops and glasses do not help to improve vision.
Panretinal photocoagulation (laser treatment) is a procedure that prevents neovascular glaucoma. A laser beam helps to lower the chances of bleeding in the eye. It also keeps the eye pressure from rising.
Neovascular glaucoma can develop three months or longer after an individual has developed CRVO. CRVO patients need regular check-ups to monitor for neovascular glaucoma. It is important because pressure can rise to dangerous levels. If there is a noticeable decrease in vision or eye pain, they should contact the ophthalmologist immediately.
The ultimate visual outcome varies from individual to individual. Some patients will have a spontaneous improvement in vision over time. It may take a few months for someone to notice any improvement. Sometimes vision can remain the same or deteriorate without treatment. However, with severe CVRO, treatment must be administered.
People will retain vision depending on two factors; if the central retinal vein was impacted by the blockage and the state of visual acuity when the blockage occurred.
Most people may experience permanent loss of vision.
People are advised to do the following to lower CRVO risk:
- Eat foods low in fat
- Get plenty of regular exercise
- Try to lose weight or maintain ideal weight
- Avoid smoking
Also, early detection of macular edema or abnormal blood vessels is advisable and vital to avoid severe vision loss.