Sherry Torkos, BScPharm
Good eyesight is something that many people take for granted. It is not until problems develop that we tend to worry about our vision. In Canada, visual impairment affects nine percent of the population aged 65 and over, or one in 11 seniors. By 2011, it is estimated that five million people will be affected..
Good eyesight is something that many people take for granted. It is not until problems develop that we tend to worry about our vision.
In Canada, visual impairment affects nine per cent of the population aged 65 and over, or one in 11 seniors. By 2011, it is estimated that five million people will be affected.
Among the leading causes of blindness are age-related macular degeneration and cataracts. While advancing age is a risk factor for certain eye diseases, it may be comforting to know that there are measures that you can take to protect your precious eyesight. Proper nutrition and lifestyle interventions go a long way in keeping your eyes healthy.
Age-related macular degeneration or AMD is responsible for 45 per cent of all visual impairments and is the most common cause of blindness in Canada. It's caused by damage to the cells in the macula (back of retina). Since the macula is responsible for providing colour and sharp/fine detail in the centre of our visual field, damage to this area can have a significant impact on vision. While the exact cause of AMD is unknown, the risk increases with age. Other risk factors include smoking, a positive family history, Caucasian, blue eyes, sunlight exposure and chemical exposure at work.
Age-related cataracts account for six per cent of Canadian seniors losing their vision and are the third-leading cause of blindness. Cataracts develop when there is damage to the proteins (crystallins) in the lens of the eye. This results in opacities or clouding of the lens and varying degrees of visual loss. As with AMD, the risk of developing cataracts increases with age, from 10 per cent under age 65, to 30 to 40 percent over age 75. Other risk factors include smoking, exposure to ultraviolet radiation, diabetes and inflammation.
Cataract extractions are one of the most common surgical procedures performed in Canada and represent a significant burden to our health-care system. As with most degenerative diseases, prevention is key to improving quality of life and saving health-care dollars. Researchers at the National Eye Institute have estimated that if the progression of cataracts could be delayed by 10 years, the number of cataract extraction surgeries per year would be reduced by 45 percent.
A Carrot a Day
Many of us were told as youngsters to eat carrots because they are good for our eyes. There is truth to this saying. Carrots are a rich source of beta-carotene the precursor to vitamin A which is essential for eye health. It has long been known that a deficiency of vitamin A can cause night blindness. A lack of zinc can also be a factor, since vitamin A requires zinc to do its job in the eye. Supplementing with vitamin A and zinc is therefore helpful in correcting night blindness in those with deficiencies.
Lutein and Zeaxanthin
While many are familiar with beta-carotene, there are other carotenoids that play a very strong role in vision, namely lutein and zeaxanthin. Lutein and zeaxanthin are plant pigments that are found in many leafy green and yellow vegetables such as kale, spinach, turnip and collard greens, lettuce, broccoli, squash, corn and brussels sprouts.
These pigments are the only carotenoids that are actually present in the macular pigment of the eye. There, it is believed that they function as antioxidants to protect against free radical damage and to absorb damaging ultraviolet light. Research conducted over the past few years has found that the risk of AMD is significantly lower with both increasing serum concentrations of lutein and zeaxanthin and high dietary intake of foods rich in these pigments.
These pigments are also found in the human lens, and preliminary research has found that they can also lower your risk of getting cataracts at about six milligrams daily. Unfortunately, a recent study conducted at McGill University has shown that our dietary intake of lutein and zeaxanthin is much less than optimal.
Another nutrient to keep an eye on is bilberry. Bilberry contains antioxidant chemicals called antho-cyanosides, which speed the regeneration of rhodopsin, the purple pigment that is used by the rods in the eye for night vision. For this reason, bilberry is used to treat night blindness. Anthocyanosides also support normal formation of connective tissue and strengthen capillaries in the body, and may improve capillary and venous blood flow.
Preliminary research has shown that bilberry may prevent cataracts and may even treat mild retinopathies, such as AMD and diabetic retinopathy. The usual dose for bilberry is 240 to 600 mg per day of a product standardized to provide 25 per cent anthocyanosides. There are no known side-effects or drug interactions with bilberry.
A few other antioxidants to keep in mind for eye health are vitamins C, E and glutathione. Vitamin C is needed to activate vitamin E, which in turn activates glutathione. Studies have shown that supplementing with vitamin C and/or E can lower the risk of developing cataracts and possibly AMD.
The recommended intake for vitamin C varies with age and nutritional status. Smokers need extra vitamin C, as do those under stress or taking certain prescription drugs. Most studies involving supplemental vitamin E have used dosages between 50 and 800 IU. Since there are possible drug interactions with vitamin E, it is wise to check with your doctor, pharmacist or other health-care provider before supplementing.
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