Age-related macular degeneration, often called AMD, is the leading cause of vision loss and blindness among people over 65 years old. Because people in this group represent an increasingly larger percentage of the general population, vision loss from macular degeneration is a growing problem.
AMD is degeneration of the macula which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula primarily is affected in AMD, central vision loss may occur. While About 1.8 million U.S. residents currently have advanced age-related macular degeneration with associated vision loss, with that number expected to grow to almost 3 million by 2020.
Dry and Wet Forms of Macular Degeneration and Current Treatments
Macular degeneration is diagnosed as either dry (non-neovascular) or wet (neovascular). Neovascular refers to growth of new blood vessels in an area, such as the macula, where they are not supposed to be. The dry form is more common than the wet form, with about 85 to 90 percent of AMD patients diagnosed with dry AMD. The wet form of the disease usually leads to more serious vision loss.
No FDA-approved treatments currently exist for dry AMD, though some are currently in clinical trials. Some evidence exists to support taking multivitamins to slow dry AMD progression. The AREDS (age-related eye disease study) showed that taking high doses of certain nutritional supplements found that it may reduce dry AMD progression by up to 25 percent.
Progression from dry AMD to wet AMD occurs in about 10 percent of cases. In wet AMD, new blood vessels grow beneath the retina where they are not supposed to be. This process is known as choroidal neovascularization. Current wet AMD treatments are designed to stop this abnormal blood vessel growth.
In 2004, the FDA approved a drug called Macugen for treating wet AMD. By 2006, a new drug called Lucentis came to market and use of this drug yielded better outcomes than Macugen. However, the primary obstacle to widespread use of Lucentis has been cost. Currently Lucentis costs about $2000 per injection, and treatment is done on a monthly basis. For this reason, another drug with a similar mechanism of action to Lucentis called Avastin began to be studied. Avastin, a cancer drug, is currently an off-label alternative to Lucentis. Since Avastin treatments are only $50 per treatment, use of Avastin has become widespread.
So which is better? Most clinical evidence shows Lucentis to yield slightly better outcomes in the treatment of wet AMD. However, the better treatment results are not considered statistically significant. Since no major adverse side effects with Avastin used to treat wet AMD have been reported, and since Avastin costs significantly less money, many retinal specialists are making Avastin their first-line drug to treat wet AMD.
In the summer of 2010, Lucentis received FDA approval for the treatment of retinal vein occlusions (RVO). Previously, much RVO treatment involved waiting to see if the disease would resolve on its own. And in central retinal vein occlusions, which account for 20% of RVO cases, no agreed upon treatments exist.
For all the positives regarding use of these new medications, patients should still know that 20% will either be nonresponders or underresponders to treatment. But considering that few wet AMD therapies were achieving much success prior to as recently as 2006, much progress has been made in the fight against this sight-threatening retinal disease.