Retinal vein occlusion
A retinal vein occlusion is a sudden blockage of a vein draining blood from inside the eye. This blockage leads to bleeding, swelling, and loss of blood flow to the retina. There are two types of retinal vein occlusion:
Branch Retinal Vein Occlusion
Occurs when only a segment of the main retinal vein is blocked, so only a portion of the retina is damaged.
Central Retinal Vein Occlusion
Occurs when the main retinal vein becomes blocked. The entire retina is damaged by this event.
Retinal vein occlusions typically occur in older patients with a history of high blood pressure and atherosclerosis. Other causes of retinal vein occlusion include vasculitis, clotting disorders, and medications such as oral contraceptive pills.
The symptoms of retinal vein occlusion include central or peripheral loss of vision. A small branch retinal vein occlusion may be asymptomatic due to overlapping vision from the uninvolved eye. Pain is not associated with a retinal vein occlusion.
A retinal vein occlusion is diagnosed with a dilated exam of the retina by an ophthalmologist. The ophthalmologist may wish to study the retinal blood vessels with photographs or by using a test called fluorescein angiography. During this test, a dye is injected into the arm and quickly travels throughout the blood system. Once the dye reaches the blood vessels of the retina, a photograph is taken of the eye. The dye allows the ophthalmologist to detect blocked blood vessels as they leak into the retina.
The best way to prevent a retinal vein occlusion is through strict blood pressure control. This become especially important when one eye has already experienced a vein occlusion.
In a retinal vein occlusion, the blood vessels in the eye leak, causing swelling of the retina. In many cases, this swelling resolves without treatment. If the swelling does not improve, it can be treated with retinal laser, which has been shown to improve vision loss. Recently, ophthalmologists have also been injecting anti-leakage medicines into the eye. These medicines include steroids such as triamcinolone acetate and anti-vascular endothelial growth factors (anit-VEGF) such as bevacizumab or ranibizumab. In recent clinical trials, these injections have been shown to reduce retinal swelling and improve vision loss. Some of these medicines have side-effects, however, so the decision to receive an injection should be discussed with your doctor.
Thanks to recent advances in retinal imaging (Optical Coherence Tomography), we are learning much more about the pathophysiology of retinal vein occlusions. Nationwide clinical studies are underway to determine the best combination of laser and injections for treatment of this disease. Pharmaceutical companies are also working to create longer lasting injections with lower side-effect profiles.