Read about the exciting new research for treatment of dry age-related macular degeneration.
Dry age-related macular degeneration (AMD) can be divided into two forms: early and late. In the early form, patients have tiny deposits under the retina, called drusen, which indicate they may lose vision in the future if the disease progresses to the late stage. Patients with late, dry AMD have a form called geographic atrophy (GA), when the vision cells (photoreceptors) in the center of the retina slowly die over time. The following article provides a brief summary of the latest treatment research for dry AMD.
For early, dry AMD, the age-related eye disease studies (AREDS1 and AREDS2) have shown that many patients can reduce their risk of vision loss by taking a specific formulation of antioxidant vitamins. The best vitamin combination is the “AREDS2” formula. Testing of additional antioxidants are underway in mice.
For late, dry AMD (GA), there is no currently approved treatment. However, several clinical trials are underway and showing promise, and studies in mice have suggested additional approaches to stop the progressive death of photoreceptors.
Immune System Strategies
The “complement cascade” is an arm of the immune system that is strongly implicated in AMD. The complement part of the immune system is thought to attack the retina. Inhibiting the complement cascade can protect the retinas of mice. While two phase III trials by Genentech targeting the complement protein called factor D in geographic atrophy patients recently failed, a phase II trial by Apellis targeting a different complement protein called C3 showed promising results.
Another approach is to try to inhibit specific immune cells with the oral antibiotic doxycycline. This is in phase II clinical trials.
Decreasing Vision Cell Workload
A different approach is to limit the workload of the photoreceptors (vision cells), thus limiting potentially toxic by-products of that work. The oral drug emixustat is designed to do this by partially inhibiting photoreceptors’ ability to sense light. A potential side effect is some degree of night blindness, or difficulty seeing in low light.
Protecting the Vision Cells
In one approach called “neuroprotection,” an implant is surgically placed into the eye so that it will slowly release a potentially protective drug. One drug being tested in a phase II trial is brimonidine, which also lowers eye pressure and is used as an eye drop in glaucoma patients.
Scientist looking through a microscopeCell transplantation is also being tested. One cell type that degenerates in GA is the retinal pigment epithelial cells (RPE). These cells are important because the photoreceptors die without them. RPE cells can be produced from other cells, then injected under the retina. Early clinical trials have suggested that this approach can be safe. Additional phase 1 and 2 trials are underway.
One drug called MacuCLEAR, an eye drop that may increase blood flow to the retina, could possibly protect against expansion of GA by providing better nourishment to photoreceptors and removing waste products.
Gene therapy experiments underway in mice provide long-term antioxidant or anti-cell death effects. Clinical trials utilizing retinal gene therapy have been successful for treatment of children with hereditary blindness.
Controlling Blood Fats
In some ways, AMD is similar to atherosclerosis, or hardening of the arteries, as lipid (fat) buildup is involved. Ongoing research is testing whether drugs that control lipids may be helpful.
Removal of Amyloid Beta
AMD also has some similarities to Alzheimer’s disease, including the accumulation of a protein called amyloid beta. Research in mice has shown that approaches to remove amyloid beta can protect the retina.
Intensive research on age-related macular degeneration (AMD) is underway, raising hopes for improved treatments.
This content was last updated on: November 28, 2017
The information provided here is a public service of the BrightFocus Foundation and should not in any way substitute for personalized advice of a qualified healthcare professional; it is not intended to constitute medical advice. Please consult your physician for personalized medical advice. BrightFocus Foundation does not endorse any medical product, therapy, or resources mentioned or listed in this article. All medications and supplements should only be taken under medical supervision. Also, although we make every effort to keep the medical information on our website updated, we cannot guarantee that the posted information reflects the most up-to-date research.
These articles do not imply an endorsement of BrightFocus by the author or their institution, nor do they imply an endorsement of the institution or author by BrightFocus.
Some of the content may be adapted from other sources, which will be clearly identified within the article.