Oxidative Stress and Your Eyes.

The Problems Eyes Have

The role of oxidative stress as the cause of degenerative changes in the eyes has generated significant interest in the use of antioxidant vitamins and minerals as a means of preventing or even treating age-related eye diseases. No fewer than six large, multicentered clinical trials are presently ongoing to study carefully the use of various nutritional supplements in the following diseases.
Cataracts
Cataract surgery is the most common surgical procedure for patients more than sixty years of age. Its economic impact on the U.S. health-care system is tremendous. In the United States eye surgeons perform 1.3 million cataract surgeries each year at a combined cost of more than $3.5 billion. It has been estimated that a ten-year delay in the development of cataracts in the U.S. population would eliminate the need for nearly half of these surgeries.2
The lens of the eye collects and focuses light on the retina. In order to perform its job properly, it must remain clear throughout our lifetime. As we age, various components of the lens may be damaged and opacities may occur, leading to age-related cataracts.
Medical researchers believe it is essential to determine if supplying adequate levels of antioxidant nutrients to the eyes early in life will preserve lens function, protecting them from cataract formation. Basic research studies support the theory that free radicals are once again the culprit; they arise from ultraviolet sunray damage and form cataracts.3
The natural antioxidants the body makes (glutathione peroxidase, catalase, and superoxide dismutase) form the eye’s primary defense system. But researchers have realized that the natural antioxidant defense system is not adequate in fully protecting the eye. In fact several clinical trials have considered the possibility that increased dietary and supplemental antioxidants may be protective against oxidative damage to the lens.4
Antioxidants found in the fluid around the lens of the eye are critical in protecting the lens itself. Thus, cataract development takes place at a much faster rate if this fluid around the lens contains low levels of additional antioxidants. The most important antioxidant in this fluid is vitamin C. Vitamin C is water-soluble and is found in high concentrations around the lens. Other antioxidants found in this fluid are vitamin E, alpha-lipoic acid, and beta- carotene.
Several epidemiological studies have demonstrated the association between the levels of vitamin C, vitamin E, and beta-carotene and the risk of developing cataracts. In Finland a case-controlled study showed individuals who had the lowest levels of vitamin E and beta-carotene had a four- to five fold increased risk of needing cataract surgery.5 Another study showed that those individuals who consumed supplemental vitamins had at least a 50 percent decreased risk of developing cataracts.6
Good medical evidence exists showing that the natural antioxidant protection of young lenses decreases significantly with age. Several different clinical studies provide evidence that when people use various antioxidant supplements, this protects the aging eye. Researchers have found the higher the level of vitamin C found in the aqueous fluid around the eye, the greater the protection against cataract formation.7 Because of its synergistic effect, alpha-lipoic acid has been shown to embellish the work of all these antioxidants in protecting the lens of the eye. Recent clinical studies also reveal that both alpha- lipoic acid and vitamin C have the ability to regenerate the intracellular glutathione so it can be used again and again.8
I only hope that over the next few years all physicians will recommend antioxidants as a way to protect against cataracts. As clinical trials begin to report their findings, we’ll know more about specific antioxidants and the supplemental levels of these antioxidants. But I believe sufficient evidence exists now to warrant encouraging patients to consume antioxidant supplements as a relatively inexpensive way to decrease this high incidence of cataract formation.
 

 

  1. ARMD Study Group, “Multicenter ophthalmic and nutritional ARMD study part one: Design, subjects, and procedures,” Journal of the American Optometry Association, 67 (1996), 12-29.
  2. A Taylor, “Effect of photooxdation on the eye lens and role of nutrients in delaying cataract,” EXS, 62 (1992), 266-279.
  3. D. Varma, “Prevention of cataracts by nutritional and metabolic antioxdants,” Crit Rev Food Sci Nutr, 35 (1995), 111-129.
  4. Taylor, “2001 assessment of nutritional influences on risk for cataract,” Nutrition, 10 (2001), 845-857.
  5. P Knekt, et al., “Serum antioxidant vtamins and risk of cataract,” British Medical Journal, 305 (1992), 1392-1394.
  6. Jacques, “The potential preventive effects of vitamins for cataract and age-related macular degeneration,” Int J Vitam NutrRes, 69 (1999), 198-205.
  7. Heseker, “Antioxidant vitamins and cataracts in the elderly” Zeitschrift Fur Ernahrungswissenschaft, 34 (1995), 167-176.

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