Nutrition and the Eye

Article submitted By Dr. Klair

Aging is a mystery, and everyone does it in their own way. Some people retain clear vision into old age, but most people, even those who are otherwise healthy, develop cataract, and some suffer macular degeneration. Nutrition plays an important role in the long term health of the eye.

The eye is subject to a lifetime barrage of light energy, which includes the white light of vision as well as the higher energy (and more damaging) ultra-violet radiation. The natural lens inside the eye absorbs much of this UV radiation and is subject to cumulative oxidative damage. Vitamin C, or ascorbic acid, is present in high concentration in the aqueous humor of the eye and is believed essential in the repair of this damage. Vitamin C is widely available in citrus fruits and beverages, as well as tomatoes and most acidic fruits. Vitamin C is not stored in the human body and so must be consumed every day. If a person doesn't eat vitamin C rich foods, then they should supplement with 500 milligrams daily. In addition to the health of the eye, vitamin C is critical to the immune system, gums, and skin.

The macula, or central vision area of the retina, has complex pigments that constantly recycle and restore the retina after exposure to light. It has long been known that beta-carotene is essential to this process. Most people know that eating carrots, a rich source of beta-carotene, is good for vision. Vitamin A is supplemented in milk, and is also present in some animal products, especially liver. Humans store vitamin A in their liver and overdosing is possible, therefore the preferred supplement is beta carotene.

Recently it has been discovered that other carotinoid pigments, called lutein and zeaxanthine, are essential to the health of the macula. These are found in carrots but are more abundant in the dark green leafy vegetables, like collard greens, spinach, and kale. Yellow fruits like squash and pumpkin are also a good source. These pigments are concentrated in the macula and play a critical role in the function and restoration of the retina.

Unfortunately, as some people age the macula deteriorates. Age-related macula degeneration (AMD) is the leading cause of new blindness in Americans over the age of 65. The risk is strongly age dependent and by age 75 there is a 5% incidence of the disease. There are two forms, "wet" and "dry," with the wet type being far more devastating to vision. Both types usually begin with the appearance of "drusen" in the macula. These usually appear in the 5th-6th decade of life and are detected by ophthalmologic examination. The American Medical Assoc. recommends screening exams every 2-4 years for ages 40-64, and then annually after age 65.

After years of anecdotal and epidemiologic evidence in favor of dietary pigments for AMD, the Age-Related Eye Disease Study, released in November of 2001, definitively supports the role for dietary supplements in macular degeneration. The study found that patients with macular degeneration who took 80 mg of zinc, 500 mg of vitamin C, 15 mg of beta carotene, and 400 IU of vitamin E daily did better than those who took placebo or other combinations over a three year follow-up.

Eat a broad variety of foods over the course of a lifetime to maintain healthy eyes. Consult an ophthalmologist for use of dietary supplements.