Age-related macular degeneration (AMD) is the leading cause of blindness in Americans over the age of 65. The disease results from damage to the center part of the light-sensitive retina, the place where light rays come to a focus in the eye. This yellow-colored center is called the macula or macula lutea, and it is the place where our most detailed vision occurs. It is an extremely metabolically active area. The cone cells are packed tightly together in the macula, and each cone cell has a nerve fiber that communicates with the visual areas of the brain. Destruction of the macula imperils central vision, and once it has deteriorated sufficiently, there is no known treatment that can restore vision.
There are two forms of macular degeneration. The common "dry" form occurs in 90% of cases. It develops slowly, and while it does not cause complete blindness, patients experience a significant loss of vision. About 10% of patients develop the "wet" form of macular degeneration. Blood vessels under the retinal begin to grow offshoots that exude and bleed into the retina, causing scarring and blockage. These new blood vessel offshoots are abnormal, and they easily become leaky. The resultant blinding can be rapid and severe. Only regular eye examinations can detect these problems before there is vision loss.
To understand causation and treatment, it is important to know that the macula has a very high concentration of yellow pigments, derived primarily from two carotenoids, lutein and zeaxanthin (Bone & Landrum 1992). This pigment layer under the retina, the RPE or retinal pigment epithelium, nourishes the macula and removes waste from the photoreceptor cells (the cones). Lack of proper nutrition can thus hasten macular destruction. Good oxygen supply has a preventive effect by stimulating RPE cells, but poor blood flow diminishes this effect. Supplementation with these two carotenoids and Omega-3 fatty acids (DHA and EPA) is essential and can acturally thicken a degenerated RPE. (reference 1, reference 2, reference 3)
Important causative factors of macular degeneration include:
• Free radical damage that occurs when ultraviolet blue light from the sun passes through the eye lens. Smoking, poor nutrition and weakened immunity all increase free radical activity.
• Deficient supply of nutrients including lutein, zeaxanthin, zinc, taurine, B vitamins, and essential fatty acids. This can be attributed to either insufficient intake or poor digestion. Multiple studies indicate the protective effect of spinach and lutein. Zeaxananthin can be made from lutein.
• Oxidized fatty waste products have also been implicated as causal factors (Spaide et al., 1999). Tiny waste products called drusen accumulate in and behind the retina and may stimulate macrophages to produce damaging inflammation. Moreover, a large epidemiological study (Beaver Dam Eye Study and Nutritional Factors in Eye Disease Study) showed that a high intake of saturated fat and cholesterol was associated with increased risk for early age-related macular disease (Mares-Perlman et al., 1995).
• Oxygen or nutrient starvation, which triggers chemical signals that initiate abnormal blood vessel growth. Examinations show that elderly patients often have less than 2/3 the blood flow to back of the eye that occurs in younger people (Abel, 1999).
Natural medicine treatment centers on improving both blood flow and macular nutrition. Patients should examine digestion and general health (see webiste discussion of digestion), take an eye vitamin rich is basic nutrients, as well as a tonic herbal supplement of sufficient potency. Important herbs include tien chi root to remove blood congestion (high doses in wet form), dang gui root to nourish the blood, triphala an antioxidant eye tonic, salvia root to improve circulation and reduce inflammation, blueberry or bilberry to provide nutrients, hawthorn to open blood vessels, lycium fruit to nourish, ginkgo leaf to increase microcirculation and improve oxygen tranport across nerve cell membranes (use with caution in wet form), ginseng root to strengthen digestion, and the following nourishing tonics good for the eye: American ginseng root, cooked and raw rehmannia, wild asparagus root, shilajatu, and elderberry. (note - Chrysalis Clinic has developed several specialized combinations such as iHeal and iFolia with these herbs )