In addition to arteries supplying blood to the retina, a highly metabolic light sensitive tissue in your eye, veins are also required to drain away oxygen depleted blood. A venous occlusion or blockage can occur, resulting from formation of a blood clot. In most cases, there is no underlying cause, aside from age related vascular changes. Risk factors include age > 60 yrs, glaucoma, high blood pressure, arteriosclerosis, diabetes, and obesity. In younger individuals, at the discretion of your physician, a work-up may be initiated to determine if you have a clotting disorder.
Symptoms of a retinal vein occlusion depend on the location of the vein involved. It ranges from asymptomatic, to severe blurring of vision that often progresses over 24 hours. Diagnosis requires a dilated eye exam from an eyecare professional. Other testing may include various forms of imaging to better assess your eye disease.
Causes of vision loss in a retinal vein occlusion:
- Macular edema: This is swelling and fluid accumulation of the macula, a portion of your retina that is imperative to your vision. This results from impaired drainage of blood and fluid from your eye by the blocked vein.
- Neovascularization with vitreous hemorrhage: New blood vessels can grow over the surface of the retina following a retinal vein occlusion which can put the eye at risk for significant complications. They may bleed into the eye causing floaters or a severe drop in vision. It is important for an eye doctor to monitor for this following a retinal vein occlusion to avoid loss of vision or pain in the eye.
- Neovascular glaucoma: New blood vessels may also grow over the trabecular meshwork, the location where fluid normally drains from the eye to allow the eye to maintain a stable pressure. Obstruction of this outflow can cause the eye pressure to increase to very high levels that can result in severe pain and further loss of vision.
Treatment of retinal vein occlusions:
- Panretinal photocoagulation: This is a method of turning down the signal your retina sends out to create new blood vessels. It involves the placement of laser burns in the peripheral retina in a pattern that reduces the production of a molecule referred to as vascular endothelial growth factor (VEGF). By turning down this signal, this type of laser is used as a treatment for neovascularization associated with retinal vein occlusions, as well as a number of other eye conditions that result in neovascularization, or new blood vessel growth.
- Focal/Grid Laser: This is the use of low power laser burns to treat macular edema. This is felt to stimulate the retina to reduce retinal swelling through the production of a molecule known as heat shock protein. This can be a very helpful adjunct to other treatment options, but requires the source of fluid leakage to be a certain distance from your central vision for use of the laser.
- Anti-VEGF medication injections: These medications target the VEGF molecule by directly binding and preventing its deleterious effects on the retina. These medications include Avastin(bevacizumab), Lucentis(ranibizumab), and Eylea(aflibercept). These medications have revolutionized the treatment of certain eye conditions, including diabetic retinopathy, age related macular degeneration, retinal vein occlusions, and others. Although they are very effective, the medication only has a certain half-life and often requires repeat treatments to control your eye disease.
- Intraocular steroids: Steroids are another effective treatment for macular edema. Careful discussion is required with your retina specialist to determine what is the best treatment option for you.
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