Although several new drugs are now available for the treatment of the exudative (wet) type of AMD, aside from cessation of smoking and a healthy diet of dark green leafy vegetables and fruits supplemented by zinc and anti-oxidant vitamins (Vitamins E, C, and beta carotene), very little is currently available to help patients with “dry” AMD to prevent progression to more serious stages of debilitating disease. Visit our page on Healthy Living to learn how patients with the dry form of AMD can potentially slow their disease. Taking the AREDS formula of anti-oxidants and zinc MAY be appropriate for some patients with the dry form of the disease. It is essential that you check with your doctor as this formula is not recommended for the early stages of the dry form of the disease.
The National Eye Institute’s Age-Related Eye Disease Study (AREDS) found that taking a specific high-dose formulation of antioxidants and zinc significantly reduces the risk of advanced AMD and its associated vision loss. Slowing AMD’s progression from the intermediate stage to the advanced stage will save the vision of many people.
In 2006 the NEI launched AREDS2, a five-year study designed to test whether the original AREDS formulation could be improved by adding omega-3 fatty acids; adding lutein and zeaxanthin; removing beta-carotene; or reducing zinc. The study also examined how different combinations of the supplements performed.
People who should consider taking the combination of antioxidants plus zinc include those who are at high risk for developing advanced AMD. These people are defined as having either:
In AREDS2, participants took one of four AREDS formulations daily for five years. The original AREDS included
Other groups took AREDS with no beta-carotene, AREDS with low zinc (25 milligrams), or AREDS with no beta-carotene and low zinc. Participants in each AREDS group also took one of four additional supplements or combinations: These included lutein/zeaxanthin (10 milligrams/ 2 milligrams), omega-3 fatty acids (1,000 milligrams), lutein/zeaxanthin and omega-3 fatty acids, or placebo. Progression to advanced AMD was established by examination of retina photographs or treatment for advanced AMD.
While most patients in the original AREDS study experienced no serious side effects from the doses of zinc and antioxidants used, a few taking zinc alone had urinary tract problems that required hospitalization. Some patients taking large doses of antioxidants experienced some yellowing of the skin. Some supplements may interfere with each other or other medications.
Removing beta-carotene from the AREDS formulation did not curb the formulation’s protective effect against developing advanced AMD, an important finding because several studies have linked taking high doses of beta-carotene with a higher risk of lung cancer in smokers. Although smokers were not given a formulation with beta-carotene in AREDS2, the study showed an association between beta-carotene and risk of lung cancer among former smokers. About half of AREDS2 participants were former smokers. “Removing beta-carotene simplifies things,” said Wai T. Wong, M.D., Ph.D., chief of the NEI Neuron-Glia Interactions in Retinal Disease Unit and a co-author of the report. “We have identified a formulation that should be good for everyone regardless of smoking status,” he said. Adding omega-3 fatty acids or lowering zinc to the AREDS formulation also had no effect on AMD progression.
As reported in 2001, the original AREDS formulation does not protect against cataract. In AREDS2, none of the modified formulations helped reduce the risk of progression to cataract surgery, although a subgroup of participants with low dietary lutein and zeaxanthin gained some protection. “While a healthy diet promotes good eye health and general well-being, based on overall AREDS2 data, regular high doses of antioxidant supplements do not prevent cataract,” said Emily Chew, M.D., deputy director of the NEI Division of Epidemiology and Clinical Applications and the NEI deputy clinical director.
“Long-term use of AREDS supplements appears safe and protective against advanced AMD,” said Chew. “While zinc is an important component of the AREDS formulation, based on evidence from AREDS2 it is unclear how much zinc is necessary. Omega-3 fatty acids and beta- carotene clearly do not do not reduce the risk of progression to advanced AMD; however, adding lutein and zeaxanthin in place of beta-carotene may further improve the formulation.” The AREDS2 study results provide physicians and patients with new information about preventing vision loss from AMD. People over 60 years old should get a dilated eye exam at least once a year and should discuss with their eye care professional whether taking AREDS supplements is appropriate.
For more information about AREDS2, visit www.nei.nih.gov/areds2.
The AREDS2 study indicated that omega-3 fatty acids such as DHA and EPA, naturally found in fish oils, do not reduce the risk of progression to advanced AMD when added to the AREDS supplement.
Several companies are conducting research to explore how, or why, early, dry AMD converts to wet AMD or progresses to the late stages of the dry form – usually referred to as “geographic atrophy”. A few different pathways such as inflammation, and/or oxidative damage have been considered, mostly involving drusen.
Small drusen usually appear early in AMD and may not result in vision loss. However, the numbers and size of the drusen may increase along with concomitant other changes such as RPE cell pathology, causing AMD to progress with resulting vision loss. Linkage of these events to the appearance of wet AMD or progression to geographic atrophy is a key question and yet under investigation. One possibility is that the drusen debris buildup leads to a diminished blood supply to the RPE and photoreceptor cells, resulting in a diminished oxygen supply (hypoxia). In an attempt to compensate for this imbalance, new, abnormal blood vessels (neovascularization) could be formed, leading to wet AMD. Continuing research may lead to more effective antioxidants, anti-inflammatory agents, etc. which could halt or even reverse the progression of early, dry AMD to the more severe wet form or to the end stage dry form.
Researchers are also very interested in genetics as a link to AMD and as a factor in progression from dry to wet AMD. Researchers have now located particular genes whose mutations are associated with an increased risk for AMD. For example, one of these genes, known as Factor H, codes for a protein (complement factor H) which is a powerful inhibitor of inflammation. People who possess an alternate version of the gene produce an aberrant complement factor H, which fails to provide adequate suppression of the complement pathway of inflammation. This means that people with the defective gene are more vulnerable to certain inflammatory processes which can lead to the development of AMD.
However, this is an area which has ignited research interest, and the longer term future may be somewhat brighter for those with dry AMD.
Prophylactic laser treatment of drusen does not apparently affect the rate of vision loss over a five-year interval according to recently reported findings from the Complications of Age-Related Macular Degeneration Prevention Trial (CAPT). CAPT was designed to assess the safety and effectiveness of low-intensity laser treatment in preventing vision loss in patients with at least 10 large drusen in both eyes at study entry. During the study, patients received treatment in one eye only, the other eye was not treated. At the end of five years, 20.5 percent of both treated and observed eyes had visual acuity scores three lines worse than at study entry.
Another study (Laser to Drusen trial) confirmed that prophylactic laser of the fellow eye of patients with neovascular AMD is not beneficial.
AMD Alliance International is not a medical organisation, therefore we can only provide general information that is not intended to be a substitute for a proper medical assessment. Please read our eye health information disclaimer.