Retina Center of OklahomaVein occlusion
The retina has veins that carry blood away from the retina (and ultimately back to the lungs and heart for oxygen replenishment and recirculation). Think of streams and rivers: tiny venules (creeks) combine to form streams or small rivers (branch veins) which combine to form one large river (the central vein, the "Mississippi River" of the retina).
For reasons that are not always clear, a blockage can develop in a vein, in either a branch vein or the central vein. Branch vein occlusions tend to happen in people over 45, often with some history of high blood pressure and perhaps diabetes and high cholesterol. Central vein occlusions tend to happen in patients over 60. When vein occlusions happen in patients under 40 we must consider a predisposition to blood clots, and we may send you to a hematologist (blood clotting doctor) for special tests.
These vein occlusions cause blood flow to "back up" into the retina, causing bleeding and swelling within the retina itself. This bleeding and swelling in the retina reduces vision.
We cannot do anything about the occlusion itself. Some exotic treatments, including injecting TPA ("clot buster" medicine) into the vein, dissecting the vein (sheathotomy), and making an incision in the optic nerve (radial optic neurotomy) have been initially greated with great fanfare but have not graduated to the level of widely-used, evidence-based interventions.
Based on the Branch Vein Occlusion Study clinical trial, the only intervention (for branch vein occlusions) based on a high level of evidence is grid laser for cases where the retinal swelling does not go away on its own after a few months (1, 2).
Based on the Central Vein Occlusion Study clinical trial, for central vein occlusions, grid laser does not help with the retinal swelling (3). Panretinal or scatter laser should be performed if the front part of the eye starts to grow abnormal new blood vessels (4).
In the past few years, retinal physicians have started to inject steroids into the eye for retinal swelling associated with branch and central retinal vein occlusion. This particular use of steroids is not FDA approved, e.g. is "off-label." Steroid injection carries risks, including cataract, glaucoma, and in-the-eye infection. The steroid injection often needs to be repeated, or the swelling may return after the steroid effect wears off after 3-4 months. A clinical trial called the SCORE study is currently underway to investigate in a scientifically rigorous fashion the merits of this intervention. The results of this study should come out in the next two years and Dr. Dahr will update his patients when those results are released. Until then, in select situations Dr. Dahr may discuss with you the the option of steroid injections.
Retinal physicians have also started to inject Avastin, a colon cancer drug, into the eye, for vein occlusions. This use of Avastin is an "off label" use of the medication. There have been some promising initial results but the "final verdict" is far from being determined. Rigorous clinical trials are being planned but the results of such trials are years away. Until then, in select situations Dr. Dahr may discuss with you the option of Avastin injections.
One last note: patients with central vein occlusions are at significant risk of developing a special glaucoma called Neovascular Glaucoma in the first year after an occlusion. This neovascular glaucoma can take away the remaining vision in the eye and can also make the eye painful. Dr. Dahr may check your eye every 1-2 months for several months to make sure such a glaucoma is not developing. If such a glaucoma starts to develop, scatter laser and/or an Avastin injection may be considered. If neovascular glaucoma is caught at an early stage, the need for glaucoma surgery on the eye can often be avoided.