Retinal Vein Occlusion

11/15/2016

Healthy Living – November 15, 2016
Michael Johnson, MD, Retinal Surgeon - Eastern Maine Medical Center
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What Is Central Retinal Vein Occlusion (CRVO)?
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:
  • Non-ischemic CRVO. This is a less serious form of CRVO, which accounts for a majority of cases.
  • Ischemic CRVO. This is a more serious form of CRVO that can lead to the development of significant complication, vision loss and possibly loss of eye.
 
Central Retinal Vein Occlusion (CRVO) Symptoms
The most common symptom of CRVO is vision loss or blurring in part or all of one eye. The vision loss or blurring is painless and may happen suddenly or become worse over several hours or days. Sometimes there is a sudden and complete loss of vision.
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.
Who Is At Risk for Central Retinal Vein Occlusion (CRVO)?
CRVO is associated with aging and is usually diagnosed in people who are aged 50 and older. High blood pressure is commonly associated with CRVO. In addition, people with diabetes are at increased risk for CRVO. People with glaucoma, high pressure in the eye, are also more likely to develop CRVO
Central Retinal Vein Occlusion (CRVO) Causes
CRVO occurs when a blood clot blocks the main vein in the retina. Narrowing of the arteries is a major factor in the development of a central retinal vein occlusion. Slowing of the blood stream, changes in the vessel wall, and changes in the blood can all contribute to the formation of a blood clot
Central Retinal Vein Occlusion (CRVO) Diagnosis
If you experience sudden vision loss, you should contact your ophthalmologist (Eye doctor) immediately. He or she will conduct a thorough examination to determine if you have CRVO. Your Eye M.D. will dilate (open) your pupils with dilating eye drops, which will allow him or her to examine the retina more thoroughly for signs of damage.
Among the other tests that your Eye M.D. may conduct are:
  • Fluorescein angiography. This is a diagnostic procedure that uses a special camera to take a series of photographs of the retina after a small amount of yellow dye (fluorescein) is injected into a vein in your arm. The photographs of fluorescein dye traveling throughout the retinal vessels show how many blood vessels are closed.
  • Intraocular pressure.
  • Pupil reflex response.
  • Retinal photography.
  • Slit lamp examination.
  • Testing of side vision (visual field examination).
  • Visual acuity, to determine how well you can read an eye chart.
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.
Central Retinal Vein Occlusion (CRVO) Treatment
Because the blocked veins cannot be unblocked, there is no cure for CRVO. Many people regain some vision even without treatment. However, even if vision does return, it rarely returns to normal.
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.
Focal laser treatment is often used to reduce swelling of the macula. With this form of laser surgery, your eye doctor applies many tiny laser pulses to areas of fluid leakage around the macula. 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 of Avastin or Lucentis in the eye may also be done. Ozurdex, a long-acting steroid, may also be used for the treatment of 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.
 
AMERICAN ACADEMY OF OPHTHALMOLOGY