Vascular Endothelial Growth Factor is implicated in both diabetic retinopathy and wet macular degeneration. Anti-VEGF medications, such as Macugen®, Lucentis® and Avastin® have changed the way we handle both diseases.
This week we’ll review VEGF and the three key anti-VEGF medications.
What is VEGF? Vascular Endothelial Growth Factor (VEGF) is a substance that is produced in the eye. There are several forms of VEGF. VEGF has three significant properties;
VEGF in Diabetic Retinopathy causes diabetic macular edema and proliferative diabetic retinopathy (see illustration). Proliferative diabetic retinopathy, by definition, is the proliferation of abnormal blood vessels on the surface of the retina and other internal structures of the eye, such as the iris. It can cause a vitreous hemorrhage.
VEGF in Macular Degeneration causes the “wet” form of macular degeneration. The “wet” form derives from the presence of “choroidal” neovascularization, or, abnormal blood vessels growing within the layers of the retina.
VEGF Binds to Receptors to cause its effects on the blood vessels in the eye. At the molecular level, the VEGF protein binds to a receptor the same way an electrical cord plugs into the wall. You could say that the VEGF protein “plugs in” to the receptor. Once activated, the receptor is then causes inflammation, angiogenesis and vascular leakage.
Blocking VEGF is possible using anti-VEGF agents such as Macugen, Lucentis and Avastin. Once blocked, the receptor can no longer be activated and the effects on the blood vessels are reversed. More specifically, once the VEGF pathway becomes blocked, macular edema may reverse, neovascularization of the retina may stop and, in macular degeneration, the choroidal/abnormal blood vessels may shrink, too.
Later this week, we’ll review each of the current anti-VEGF medications.