Leaky Blood Vessels
The most recent development, and the best development, against wet AMD are anti VEGF drugs. The difference between wet AMD and dry AMD is that wet AMD's progression is faster and its effects on vision are worse. It is called "wet" because the disease causes leaky blood vessels to grow out of the choroid, which is a group of vessels that nourish the retina. These vessels grow in response to a call for help that says the retina lacks blood flow. VEGF puts that activity in motion. VEGF is released by the cells that line the blood vessels and it causes the body to grow small capillaries very quickly. These capillaries do not grow like normal vessels do. Instead, they are like hundreds of leaky garden hoses under the retina.
VEGF Drugs Also Fight Cancer
The retina is damaged when proteins, blood, and its components leak under the retina. The damage happens as a result of scarring and the fluid that separates the retinal layers and creates space between them.
Anti VEGF drugs are usually used to fight cancer. When there is a good blood supply, tumors thrive. Once doctors understood the way VEGF works and what it does to the eye, they thought they could try these cancer drugs for this purpose.
Three drugs are used in the eye. One is used off label, and the other two are approved by the FDA for use in the eye. All of these drugs are able to help prevent vision loss. Often, patients who are put on this type of therapy notice an improvement in their vision. The drugs in this therapy act as VEGF antibodies and bind to VEGF, which keeps it from binding to endothelial cell receptors.
Approved and Off-Label Anti-VEGF Drugs
Macugen (pegaptanib) - The FDA approved this drug in 2004 for AMD treatment. It is selective for the VEGF form that is in AMD, and it does not bind to other types. Of all the drugs used to treat wet AMD, this is the least used.
Lucentis (ranibizumab) - The FDA approved this drug in 2006 to treat wet AMD. It does not bind specifically to VEGF. The drug was designed to be as small as possible so it can be used in the eye with limited systemic side effects. It has a greater affinity than bevacizumab, which is its parent molecule.
Avastin (bevacizumab) - The FDA approved this drug for colon cancer, but not for the eye. Like Lucentis, Avastin does not bind to VEGF specifically. Many physicians use it because it is about 50 times less expensive than a Lucentis injection. It has not been proven that Lucentis is any better than Avastin in treating this disease. The NEI conducted a study called the Age-Related Macular Degeneration Treatment Trial to compare the results between Avastin and Lucentis.
For all anti VEGF treatments, patients must visit an opthamologist every month for an injection. Most side effects come from the injection, and usually, they are mild. Often, the side effects are pain and blurred vision, which is temporary. The risk of a serious side effect, like an infection, is about 1 in 4,500.