Retinitis Pigmentosa - Macular Degeneration

Are there areas of research that look promising for potential treatments for Macular Degeneration?

Yes. Through the efforts of Retina International , the number of highly qualified scientists working full-time on Macular Degeneration and other diseases of retinal degeneration continues to grow. With financial support from Retinal patient groups, clinical specialists and laboratory scientists at more than 40 medical and research institutions in the USA, Europe and South Africa, are involved in more than 110 research projects related to retinal degenerations.

Antioxidants and Vitamin Therapies

One working hypothesis is that a cause or contributing factor to Macular Degeneration involves the formation of chemicals in the body called free radicals. Free radicals are thought to result, in part, from exposure to sunlight and other forms of ultraviolet light. They cause cellular damage by taking electrons from molecules in healthy cells. This process, called oxidation, has been linked to a variety of health problems including heart disease and cancer. Substances called antioxidants may counteract the oxidation process; the body produces its own antioxidants, and these are helped by antioxidants that we ingest through food or vitamin supplements. Vitamins C, E and carotenoids, including beta-carotene, are examples of potent antioxidants. The AREDS study showed some benefit through the supplementation of high doses of Vitamin C, Vitamin E, Beta carotene and Zinc. However, people who smoke should not take Beta carotene as it increases the risk of lung cancer. Lutein supplementation may offer some reduction to glare sensitivity. Lutein is a structural component of the central retina and is found in leafy green vegetables. Self medication is not advised and the opinion of your eye specialist should be sought.

Retinal Cell Transplantation

Transplantation of retinal cells has shown some encouraging results in animals, although it is important to emphasize that this is not yet a treatment available for use in humans. Retinal cell transplantation is still in preliminary stages of investigation in the laboratory. Before a procedure can be tested in humans, long-term beneficial effects must be proven and possible side effects must be determined. Such research might take several more years.

The good news is that studies so far have found that when photo receptor cells are transplanted into the retinas of animals, some features of normal photo receptors are either maintained or develop after transplantation. However, there is not yet conclusive evidence that retinal cell transplants or similar procedures in animals with a retinal degeneration result in long-term improved or restored vision. Nevertheless, the research done so far has been promising enough for the American Foundation Fighting Blindness to expand a grant award programme aimed at scientists who are investigating several areas of basic science that could lead to new therapies that might repair or replace damaged retinal cells.

Special Challenges in AMD Research

Because AMD does not develop until late in life, and all body tissues undergo changes associated with ageing, it is difficult to determine which eye findings are normal in those over the age of 50, and which may be predictive of AMD. The American Foundation, along with the American National Eye Institute, is working to define normal ageing, classify AMD types, define genetic components, define risk factors, develop new diagnostic techniques, analyse eye tissue layers and how they interact, and develop animal models that imitate human AMD.

Gene Therapy

As researchers identify more of the mutant genes that contribute to Macular Degeneration, it becomes possible to think about curing the defect at the most basic cellular level. Gene therapy is what many scientists feel is the answer of the future for many forms of retinal degenerations. It is based on a simple logic: if a gene is defective, replace it with one that is not defective. While this may sound simple, the actual procedure of gene therapy is very complex.

Gene therapy might be described as a form of drug therapy in which the "good" gene itself is the drug, which is introduced into the body to replace the "bad" gene. There are a number of reasons that retinal degenerations are diseases that seem particularly suited to the use of gene therapy. First and foremost, some of the defective genes for early onset inherited Macular Degeneration have been identified. Also, there are a number of applicable animal models in which gene therapy can be tested for effectiveness and safety. And the outcomes of gene therapy can be tested by reliable and non-invasive visual examination of the retina. Finally, a treated eye can be compared to an untreated eye in the same patient, giving researchers the ideal conditions for conducting a controlled scientific experiment.

While all of the above factors make gene therapy a promising future approach for treating Macular Degeneration, there are still many obstacles. One key question is how to actually introduce the DNA of the good gene into diseased cells. Researchers have found that a neutralized virus can act as a transporter of the gene to the degenerating photo receptor cells, which seem to be particularly good targets for this type of gene transfer.