There have been some significant developments regarding therapy for wet macular degeneration.
This includes the use of molecules that inhibit one of the growth factors that cause new blood vessels to grow (anti-vascular-endothelial-growth-factor or anti-VEGF molecules). Avastin was developed as the first antibody to vascular endothelial growth factor.
At the time Avastin was developed, the company made a scientific assumption that the molecule was too large to pass into the retina, so it was primarily developed for cancers and other areas using anti-vascular-endothelial-growth-factor therapy. Lucentis was developed as a fragment of the Avastin molecule using the same active sites of vascular-endothelial-growth-factor inhibition. It was developed as a small molecule to pass in and out of the retina more quickly.
Avastin was released in 2004 for cancer treatment. Ophthalmic researchers began using it for the eye and discovered that it is a very effective drug. In fact, they discovered a secondary mechanism by which the larger molecule can be passed into the retina. The clinical effectiveness of Avastin across the country appears to be roughly equivalent to Lucentis, the smaller molecule. Lucentis, since it is a small molecule, both enters the retina easily and leaves it quite quickly, requiring monthly injections for two years to maintain its benefit. Avastin, on the other hand, has shown a much longer duration. After one or two initial injections of Avastin, often patients are maintained on injections once every two to three months.