Corneal avascularity is due to soluble VEGF receptor-1

Bloodless evolution The cornea is one of the few tissues in the body with no blood vessels flowing through it. This blood-vessel-free island is often used to test anti-angiogenic therapies for cancer, arthritis, atherosclerosis, diabetes and other diseases driven by pathological angiogenesis. This lack of blood vessels is remarkable because of the highly vascular nature of the surrounding tissues; doubly remarkable because the cornea has now been found to contain large amounts of the potent angiogenic molecule VEGF-A (vascular endothelial growth factor). This discovery has led to a finding that could be important in terms of drug design: a VEGF-A trap known as soluble VEGFR-1 is also present in the cornea and is singly responsible for the absence of blood vessels there. Intriguingly, the few known organisms that have a vascularized cornea (manatees, mutant mice, and some aniridia patients with Pax6 mutations) are all deficient in corneal soluble VEGFR-1.