Vision loss is a serious complication of aging. Age-related macular degeneration, or AMD, a disruption of the cells in the macula, the central point of the retina, affects 10 million Americans, the Massachusetts Eye and Ear Infirmary says. The macula contains the cells responsible for clear, sharp vision. Macular degeneration occurs in two forms, dry and wet, with dry nearly always preceding the more severe wet form. Dry AMD also affects more people, with over 90 percent of cases of AMD being dry. One or both eyes can develop the disease. Treatments differ, depending on which type of macular degeneration is present.
Diagnosis
Dry and wet AMD are treated differently, so it's important to know which type is present before starting treatment. Medical practitioners look into the eye with special microscopes after the eye is dilated. Drusen, yellow fatty deposits caused by aging of the layers of the retina, are seen in diagnosing dry AMD. Wet AMD can be diagnosed by an exam and by photographic tests that check for leaking from any abnormal blood vessels that form in wet AMD.
Dry AMD Treatment
No treatment for dry macular degeneration exists in 2010. However, treatments aimed at preventing intermediate dry AMD from worsening or becoming wet do exist. A vitamin formulation known as the AREDS (Age Related Eye Disease Study) formula has been marketed since clinical trials were conducted by the National Eye Institute. The AREDS formula consists of 500 milligrams (mg) of vitamin C, 400 international units (IU) of vitamin E, 15 mg of beta carotene, 80 mg of zinc and 2 mg of copper. Moderate or severe vision loss was reduced by 25 percent in the study, the Mayo Clinic says.
Wet AMD Intravitreal Injections
Injections given through the white part of the eye, the sclera, into the vitreous, the gel that forms the central part of the eye, treat wet AMD. Two medications, Lucentis and Avastin, treat the disease by attacking vascular endothelial growth factor (VEGF) proteins that help new abnormal blood vessels form under the macula; the abnormal vessels swell and bleed. Genentech makes both medications; only Lucentis is FDA-approved for use in the eye. Avastin is used "off label," meaning it hasn't undergone clinical trials in the eye, but the two drugs are very similar. Both are given frequently, every month or so, for several months. Medical practitioners numb the eye before injection, which takes just a few seconds to do.
A study comparing Lucentis with an older treatment called photodynamic therapy (PDT) showed 95 percent of patients had no vision loss after one year on Lucentis, and 40 percent gained 3 or more lines on the reading chart, according to the University of Alabama at Birmingham.
Laser Treatment for Wet AMD
Until Lucentis was approved, the standard treatment for wet AMD was PDT, which is still used to treat some types of wet AMD, sometimes in conjunction with Lucentis or Avastin. A drug called Visudyne, which is activated by intense light, is injected into the arm. After the infusion, a cold laser is aimed at the abnormal blood vessels, where Visudyne accumulates shortly after infusion. The laser activates the drug, which coagulates and closes off the leaking vessels.
Current Research
Preventing the development of dry AMD or stopping the progression to wet AMD would be more effective than curing the disease once it begins. Studies into the effectiveness of Omega 3 fatty acids and lutein to treat dry AMD continue in 2010. Preliminary work into gene identification and stem cell treatments for AMD may lead to improved cure rates of AMD in the future, the University of Nebraska Medical Center says.
