Age Related Macular Degeneration
Age related macular degeneration is a disease that affects the macula portion of the retina which is the central vision of your eye. It affects older patients and is due to the accumulation of metabolic waste products known as lipofuscin in the central portion of the retina called the macula. Lipofuscin coalesces to form drusen which are visible on dilated eye exams of the retina. This drusen accumulation is what is known as age-related macular degeneration (AMD). Like diabetes, there have been genes identified with AMD that increases your risk to develop AMD. However, many patients that do not have these identified genes may still develop AMD. AMD has two types, the dry AMD form (known as non-neovascular AMD) and the wet AMD form (known as neovascular AMD).
Dry AMD is slowly progressive with the formation of drusen and degeneration of the retinal pigment epithelium (RPE). The RPE is a layer of cells under the retina that provides nutrition and eliminates waste products of the retina. The formation of drusen and loss of RPE is what causes your vision to be distorted, blurred, or missing. This form of AMD, the dry type, progresses very slowly over many years to cause vision loss.
The wet AMD form is a more aggressive disease causing rapidly progressive vision loss. The vision loss is due to abnormal blood vessels growing underneath the retina that leak fluid or bleed. This fluid or blood underneath the retina impairs its ability to function, resulting in vision changes such as distortion, blurriness, or loss of central vision. If left untreated, a scar develops resulting in permanent irreversible vision loss.
At present, there is no cure for age-related macular degeneration despite extensive ongoing research studies. However, there are treatments that can preserve your vision. Treatments for dry AMD are presently aimed at slowing the development of drusen. There currently are no FDA approved drugs for the treatment of dry AMD. However, large studies by the NEI known as AREDS have demonstrated the benefit of eye vitamins at decreasing the risk of dry AMD progressing to wet AMD. In addition, studies have shown that smoking and tobacco products significantly increase the risk of dry AMD converting to wet AMD.
In the past, thermal laser treatment was used for treating wet AMD. While the laser would destroy the abnormal vessels growing underneath the retina, it also creates a scar and often did not restore the vision lost. Currently, wet AMD can be successfully managed with anti-VEGF therapies such as Avastin, Lucentis, or Eylea and a newer cold laser called photodynamic therapy (PDT). These drugs inhibit abnormal vessel growth and causes the bleeding or leaking abnormal vessels to regress. These drugs have revolutionized the management of wet AMD because it not only eliminates the abnormal vessels without creating a scar such as laser therapy, it also restores and preserves vision when detected early.
Because the eye is an immunoprivileged site meaning that medications taken by mouth do not penetrate well into the eye, the medicine has to be delivered by an injection into the eye. All these medicines simply convert wet AMD which can cause rapid vision loss back to dry AMD. However, repeated injections are often necessary since the underlying disease process remains and abnormal vessels may grow back to bleed or leak fluid. There are many different subtypes of wet AMD. It is important to see your retinal specialist to determine a personalized tailored therapy in selecting what medication is best for you and your eye.