Further to my post last month about the use of Avastin, a bowel cancer treatment, being used to treat macular degeneration. I was wondering how anybody could come up with the idea of applying a bowel drug to the eye. It's not the sort of thing that could happen by accident. Orac has a post today, with a picture of an eye (be still my beating heart), which explains how angiogenesis - the formation of new blood vessels - helps tumours to grow. Angiogenesis is helped by small proteins belonging to the vascular endothelial growth factor (VEGF) family. Avastin is an anti-VEGF antibody that shuts off the neovascularisation to the tumour, starving it of nutrients. Obviously, what works in the bowel should work in the eye too, and that's how the connection was made.
The interesting thing about VEGF is that a receptor for this protein, called VEGFR-3 is found in large amounts on healthy corneal epithelium. It binds with VEGF-C & D and seems to stop blood growth on the cornea, thus keeping it clear and transparent for us to see through.