Central Retinal Vein Occlusion (CRVO) occurs when the main retinal vein is blocked. Because the blood can no longer travel out of the retina smoothly, the retina becomes filled with blood and swollen. If the blockage is partial, the retina may continue to function adequately. If the blockage is more severe, permanent retinal damage may occur with loss of vision. Central retinal vein occlusions occur most commonly in people who have high blood pressure, diabetes or glaucoma. Occasionally, the damage to the retina will result in abnormal new vessel growth. Further visual loss can occur if these abnormal blood vessels break and bleed into the vitreous cavity, causing a vitreous hemorrhage.
CRVO can also lead to Neovascular Glaucoma, a condition in which abnormal blood vessels grow on the iris or colored part of the front of the eye. These abnormal blood vessels can block the flow of fluid from the eye and cause the eye pressure to become very high. Neovascular glaucoma can cause pain, halos around lights, and rapid loss of vision.
Patients with central retinal vein occlusion usually have blurred vision from retinal hemorrhage and swelling. Spots, strands or curtains in the vision may occur due to vitreous hemorrhage. Eye pain may be caused by neovascular glaucoma.
In addition to a dilated eye exam, a test called Fluorescein Angiography may be required. During this test a dye is injected into a vein in the arm. Special photographs are taken of the retina as the dye passes through the eye. Blocked or abnormal blood vessels will become detectable to the physician. Optical Coherence Tomography (OCT), a scanning laser which images a slice or cross section of the retina, may be performed to determine if macular edema is present. These tests aid the diagnosis and may help determine the type of treatment needed.
Intravitreal Drug Therapy has been proven to improve outcomes in patients with CRVO. Intravitreal Drug Therapy involves placing medication into the vitreous, or main cavity of the eye. The injected medication acts upon the damaged blood vessels to reduce leakage and resolve macular edema. Intravitreal drug therapy may also be recommended to cause regression of new blood vessels. Intravitreal drug therapy may involve ongoing treatments; sometimes over many years.
Laser Treatment is often required when CRVO causes complications such as abnormal, new blood vessel growth. Laser treatment is used to reverse the growth of the new blood vessels. If untreated, these abnormal blood vessels can cause vitreous hemorrhage and glaucoma. Laser may be applied in several sessions.