by Anne M. Hanneken, Ophthalmologist
It can begin with a barely perceptible loss of vision. Threading a needle may seem more difficult than it used to be, or the squares of a crossword puzzle may be harder to see. Eventually, nearly all central vision may be gone.
It is macular degeneration, an eye disease that is the leading cause of blindness in patients over age 55. One out of three people age 75 and older suffers from the disease, and the number of cases is expected to double as the population ages.
As its prevalence has grown, so has awareness of the disease and the sense of urgency to find a treatment or, better yet, a cure.
Macular degeneration is a disease that affects the portion of the eye known as the macula. The macula is part of the retina, which is the inner lining of the eye that absorbs and processes light.
Think of your eye as a camera. The retina is the film that your eye uses to take pictures. The macula surrounds the central part of the retina and helps you “focus” the camera for reading and tasks that require close, concentrated vision.
Macular degeneration is caused by progressive deterioration of a region that nourishes the retina, known as the retinal pigment epithelium (RPE). This leads to degeneration of part of the retina itself.
As a result, patients have difficulty with central vision. Activities that require central focusing become difficult or impossible. Fortunately, peripheral vision usually isn’t affected, and very few patients lose all of their vision.
In the earliest stages of macular degeneration, small protein deposits build up under the cells that nourish the retina. Because these deposits cause no symptoms, patients are not aware of them. They can be seen only during a careful eye examination.
As the condition progresses, the cells that nourish the retina begin to deteriorate. This leads to the “dry form” of macular degeneration and accounts for up to 90% of macular degeneration cases. In most cases, degeneration occurs very slowly, and central vision remains stable for years.
In the remaining 10%, however, vision may change suddenly, with marked distortions and wavy lines. This signals the development of abnormal blood vessels which grow under the retina around the cells that nourish it. This “wet form” of macular degeneration is recognized by the appearance of blood and scar tissue under the retina.
While there is currently no treatment to prevent the development of macular degeneration, recent clinical research has suggested that certain nutrients may help reduce its progression. A large, 10-year clinical trial sponsored by the National Eye Institute suggested that antioxidants could reduce the progression of macular degeneration by up to 28% over a five-year period.
In another study, patients who ate three servings of spinach per week had a 43% lower risk of developing macular degeneration. Diets high in antioxidant carotenoids — colored pigments normally present in the macula which serve as a kind of protective coating against light damage — are associated with a decreased risk of the disease. Lutein and zeaxanthin are two such carotenoids.
Flavonoids, another group of natural antioxidants present in high concentrations in a wide range of fruits and vegetables, also are being studied as potential beneficial nutrients for the prevention of macular degeneration.
Flavonoids evolved to protect plants from the oxidative damage induced by chronic exposure to ultraviolet light. They are believed to have many health benefits, including protection from cardiovascular disease and cancer.
In a collaborative effort between The Scripps Research Institute and The Salk Institute, Scripps Health researchers have been testing a variety of nutritional flavonoids to identify which specific compounds protect cells from the type of injury which leads to macular degeneration.
Based on early findings, these fruits and vegetables with the highest concentrations of flavonoids were considered to be most effective.
- Veggies: spinach, wild greens, onions (especially yellow), tomatoes, celery, hot peppers and chives
- Fruits: cranberries, cherries, blueberries, strawberries, kiwi, grapes, apples and citrus juices
- Herbs: thyme, parsley, peppermint and mint
This Scripps Health and Wellness tip was provided by Anne M. Hanneken, M.D., ophthalmologist with Scripps Memorial Hospital La Jolla