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Cataracts, the world's leading cause of blindness, cause visual impairment in more than 3 million people in the U.S. and 50 million globally. Data suggest that smoking causes 20 percent of all US cataract cases.
A cataract is a clouding of the natural lens, the part of the eye responsible for focusing light and producing clear, sharp images. As the lens becomes more opaque, seeing out of your eye becomes more difficult. Blindness could be the end result of cataracts. A surgical lens transplant will then be required to restore eyesight.
Research confirms that smoking boosts a person's risk of developing cataracts. Starting in 1982, epidemiologist William G. Christen of the Harvard Medical School in Boston and his team monitored 17,824 male physicians who showed no sign of cataracts at the outset of the study.
Over the next five years the team monitored the volunteers, identifying 557 cases of cataracts, the Science News reported. The men who reportedly smoked at least a pack (20 cigarettes) per day at the study's start ran a significantly greater risk of cataracts than did men who had never smoked. Smokers faced an estimated 200 percent increased risk of developing a posterior subcapsular cataract and an estimated 100 percent increased risk of nuclear sclerosis cataract. (A posterior subcapsular cataract is a visually disabling condition that begins at the back of the lens, while a nuclear sclerosis cataract, a less serious form, begins in the nucleus, the center of the lens.)
Susan E. Hankinson — also at the Harvard Medical School — and her colleagues describe a similar study of more than 50,800 women who participated in the Nurses' Health Study, a trial of registered nurses that began in 1976.
After monitoring the women for eight years, the researchers identified 493 cases of cataracts. Compared with non-smokers, women smoking at least 30 cigarettes per day during the study had about a 60 percent greater risk of developing cataracts serious enough to require surgery.
Free radicals are responsible for most cataracts. Recent research shows that smokers have lower blood levels of antioxidants compared to non-smokers, substances that protect cells from damage caused by free radicals. Compared with non-smokers, smokers may thus sustain greater free-radical damage to the lens.
Quit smoking today!
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