14 Dec VEGF Causes Blindness in Diabetes and Macular Degeneration
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;
- Causes Inflammation
- Causes angiogenesis (creates new blood vessels)
- Causes vascular permeability (blood vessels leak)
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 Causes Retinal Neovascularization
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 Causes Choroidal Neovascularization
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.
“Randy”
Ophthalmologist, Retina Specialist
Fairfax Virginia
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Aissa Dirawatun
Posted at 09:35h, 14 DecemberIs there a way to block every single receptor in the retina so wet AMD and/or diabetic retinopathy doesn’t occur?
Would preventative Avastin injection (for example) help patients with history of wet AMD or early diabetic retinopathy?
Randall V. Wong, M.D.
Posted at 09:47h, 14 DecemberLater this week, I’ll review the differences between Avastin, Macugen and Lucentis. One of the differences is the different types of VEGF that are blocked. Not all VEGF is bad. Some VEGF is necessary for normal growth and development. Having said that, it seems that it is safe to block most of the VEGF variants in the eye. The drug is short lived, lasting only about 4-8 hours, depending on the drug. This answers your second part, preventative injections probably won’t work since the drug isn’t in the eye too long.
Thanks for reading…………and commenting.
r
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Posted at 13:54h, 01 May[…] beat a dead horse – This is why we are using intraocular injections to deliver steroids and anti-VEGF medications to treat macular degeneration and diabetic retinopathy. These drugs do not get into the eye via […]
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