CURRENT TREATMENTS

Dry AMD

The National Eye Institute’s Age-Related Eye Disease Study (AREDS) found that high daily doses of certain vitamin supplements can help slow the progression of intermediate AMD to advanced AMD.

The specific daily amounts of antioxidants and zinc recommended include:

— 500 milligrams of vitamin C

— 400 International Units of vitamin E

— 15 milligrams of beta-carotene (often labeled as equivalent to 25,000 International Units of vitamin A)

— 80 milligrams of zinc as zinc oxide

— 2 milligrams of copper as cupric oxide

The study showed a benefit only in people with either bilateral intermediate disease or those in whom one eye had already progressed to advanced disease. No statistical benefit was found in people with early stages of AMD. Additionally, some individuals with a history of smoking should not take beta-carotene.35

The levels of antioxidants and zinc in the study were considerably higher than the amounts in any daily multivitamin and are difficult to achieve from diet alone. However, previous studies also have suggested that people whose diets include green, leafy vegetables lower their risk of developing AMD.36

Wet AMD

Presently, three types of treatments have been scientifically proven in large clinical trials and are approved by the FDA for the treatment of wet AMD: laser photocoagulation, photodynamic therapy with verteporfin, and injections of anti-vascular endothelial growth factor (VEGF) agents into the eye.

Laser photocoagulation – This procedure uses a laser to destroy the fragile, leaky blood vessels, preventing further loss of vision. Only a fraction of those with wet AMD – 10 percent at most of all wet AMD cases – can be treated effectively with laser surgery. Since the blood vessels are beneath the retina, the laser has to pass through the retina to reach them, resulting in damage to the retina as well. Laser is therefore more effective for leaky blood vessels that have developed away from the central part of the macula, known as the fovea. The risk of new blood vessels developing after laser treatment is high, and repeated treatments may be necessary. In some cases, vision loss may progress despite repeated treatments. Since the advent of photodynamic therapy, laser treatment is rarely used for central lesions and is largely used to treat lesions whose borders lie outside the center of the fovea.

Photodynamic therapy – This procedure was developed so that the laser can go through the retina with no or minimal damage. It includes the use of a light-activated drug called verteporfin, which is injected into a vein in a person’s arm, travels through the body to the eye and accumulates in the area of new blood vessel growth. Low-energy light in a laser beam is then delivered to these vessels, activating the drug, which then damages or destroys the new blood vessels, leading to a slower rate of vision decline.

The clinical studies of photodynamic therapy indicated that wet AMD could be classified into three main subtypes based on the appearance of the vascular lesions on fluorescein angiography:

Photodynamic therapy has been effective in treating very small lesions associated with all three subtypes in clinical studies. Currently, it is approved by the FDA to treat predominantly classic wet AMD and selected forms of minimally classic and occult AMD.

Anti-Vascular Endothelial Growth Factor (Anti-VEGF) Agents

What Is Angiogenesis and What Role Does It Play in AMD?

Angiogenesis is the increased growth of blood vessels associated with numerous diseases including AMD. Certain proteins, such as vascular endothelial growth factor (VEGF), have been shown to play an important part in abnormal blood vessel growth and blood vessel leakage, two of the primary pathological processes responsible for the vision loss associated with wet AMD.37, 38 When the abnormal vessels leak blood or other fluid, they cause blurring in the central vision and damage to the photoreceptors, often resulting in the development of a scar under the retina.

Among the new treatments wet AMD are anti-angiogenesis drugs, which are aimed at decreasing blood vessel growth and leakage that may damage the retina. Most of these do so by blocking the VEGF protein and are, thus, “anti- VEGF” or “VEGF inhibitors.” Others are steroids that may modify the behavior of the abnormal blood vessels.

Pegaptanib Injections - (Macugen®, (OSI)™ eyetech))

is an aptamer that binds to one form of VEGF), a potent stimulator of new vessel growth and leakage, and it neutralizes VEGF activity. It is delivered by injection into the eye every six weeks. The drug has been approved for the treatment of all three types of wet AMD – predominantly classic, minimally classic, and occult.39 The duration of treatment with pegaptanib is quite variable and determined by the response of the individual patient. The primary benefit of the drug is the preservation of vision rather than genuine significant improvement.   

Ranibizumab Injections - (Lucentis ®, Genentech Inc and Novartis Ophthalmics) is an antibody fragment to VEGF, which also binds to and inhibits VEGF. The drug is delivered by injection to the eye every four weeks to treat all types of wet AMD.   Recently completed trials have shown that treatment with ranibizumab can effectively halt the vision loss associated with AMD and result in significant improvement in vision, by at least 3 lines, in 30 to 40% of patients.  This drug was just approved for use in all forms of exudative AMD as well.