How to choose foods that can help prevent eye disorders

The role of antioxidant nutrients and bio­fla­vonoids in vision loss and other degenerative problems associated with aging is becoming increasingly clear. With advancing age, the production of free radicals, those unstable molecules that form when the body uses oxygen, increases. Free radicals can cause eye damage similar to that resulting from exposure to radiation, and can also contribute to such disorders as cataracts and macular degeneration. Cataracts develop when the lens yellows, hindering the passage of light rays through it. Vision becomes hazy, cloudy or blurry. If untreated, the lens may become completely opaque, resulting in blindness. Here are some tips on choosing foods that can help stave off eye disorders.

Although aging is the most common cause of cataracts, they can occur at any time of life. Smoking and diabetes can hasten their development.

• A diet that provides ample antioxidants — in particular, vitamins C and E and the carotenoid lutein — appears to slow their progression. At least one study has shown that the prevalence of cataracts in people who took vitamin C supplements for at least 10 years was significantly lower.

Macular degeneration, an­other eye disease that comes with aging, is one of the most common causes of legal blindness among older North Americans. It entails a gradual, painless deterioration of the macula, the tissue in the central portion of the retina. The first symptom is usually blurring of central vision but eventually side vision can also become limited.

• Recent research suggests that a diet high in antioxidant nutrients may help prevent or slow the disorder.
• Lutein and zeaxanthin are two antioxidants that may help. Lutein is found in green leafy vegetables such as broccoli, kale, Swiss chard and watercress, as well as in corn, peas and egg yolks. Zeaxanthin is also found in greens, red peppers and corn.
• Research also shows that a diet high in saturated fats increases the risk of age-related macular degeneration. Scientists theorize that saturated fats may clog the arteries in the retina in the same way that they contribute to atherosclerosis in larger blood vessels, such as the coronary arteries. Eating fish more than once a week significantly reduces the risk.

• Certain similarities between macular degeneration and diabetic retinopathy — the infiltration of the retina with tiny, ruptured blood vessels — suggest that antioxidant nutrients may also be beneficial in this common complication of diabetes.
• Diet is critical in maintaining tight control of blood glucose levels, which also reduces the risk of diabetic retinopathy.

The eyes need vitamin A or its precursor, beta-carotene, as well as bioflavonoids, to make the pigments that absorb light within the eye. A deficiency in vitamin A impairs the eye's ability to adapt to darkness and leads to night blindness. This does not entail a total loss of night vision, but rather difficulty seeing well in dim lighting.

• Vitamin A deficiency is rare in the Western world, but it remains a problem in many underdeveloped countries.
• Organ meats, fortified margarine, butter and other dairy products are good sources of vitamin A.
• Dark yellow or orange foods, such as carrots, sweet potatoes and apricots, as well as dark green leafy vegetables, are the richest sources of beta-carotene, which the body converts to vitamin A.
• Failing night vision should not be self-treated with vitamin A or beta-carotene supplements; the problem may stem from a digestive or malabsorption disorder that prevents the body from using the vitamin.