The retina—the layer of light-sensitive cells at the back of the eye—is nourished by blood flow, which provides nutrients and oxygen that nerve cells need. When there is a blockage in the veins into the retina, retinal vein occlusion may occur.
Central retinal vein occlusion (CRVO) is a blockage of the main vein in the retina. (Blockage of the small veins in the retina is called branch retinal vein occlusion, or BRVO.) The blockage causes the walls of the vein to leak blood and excess fluid into the retina. When this fluid collects in the macula (the area of the retina responsible for central vision), vision becomes blurry.
There are two types of CRVO:
Floaters in your vision are another symptom of CRVO. When retinal blood vessels are not working properly, the retina grows new, fragile vessels that can bleed into the vitreous, the fluid that fills the center of the eye. Blood in the vitreous clumps and is seen as tiny dark spots, or floaters, in the field of vision.
In severe cases of CRVO, the blocked vein may cause painful pressure in the eye.
Ischemic CRVO can also cause neovascular glaucoma. This type of glaucoma is caused when abnormal blood vessels begin to grow inside the eye, causing the pressure in the eye to rise. Neovascular glaucoma is a serious condition that can cause pain and lead to severe vision loss. It may take three months or longer after CRVO occurs for neovascular glaucoma to appear.
Among the other tests that your ophthalmologist may conduct are:
In addition, you may be tested to determine your blood sugar and cholesterol levels. For patients under the age of 40 with CRVO may be tested to look for a problem with clotting or blood thickening.
Finding out what cause the blockage is the first step in treatment. Your Eye M.D. may recommend a period of observation following your diagnosis. During the course of CRVO, many patients will have swelling in the central macular area. This swelling, called macular edema, can last more than one year.
The main goal of treatment is to stabilize vision by sealing off leaking blood vessels that interfere with the proper function of the macula. Treatment with injections anti-VGEF dugs in the eye may also be done. Long-acting steroid, may also be used for the treatment of macular edema.
Scatter (pan-retinal) laser treatment can be used to seal or destroy abnormal blood vessels, stopping them from growing. In this type of surgery, the Eye M.D. may make hundreds of small burns to the blood vessels. It may require two or more treatments to complete the process.