CHICAGO -- In addition to other health problems, cigarette smoking appears to increase the risk for cataracts, the leading cause of blindness, researchers reported Tuesday.
Two new studies published in the Journal of the American Medical Association found male and female smokers faced significantly increased risk for developing cataracts.
Cataracts are a progressive disease in which the lens of the eye loses its clearness, ususally occurring after age 50. The condition can be treated by removing the clouded lens, requiring patients to wear special contact lenses.
Although more research is needed to explain how smoking causes cataracts, the new findings provide another reason to quit smoking, researchers said.
'It appears that the litany of ills associated with smoking is growing, as we add to it cataracts, the world's leading cause of blindness,' said Sheila West of the Johns Hopkins Hospital in Baltimore.
In the first study, Harvard Medical School researchers studied 17,824 U.S. male doctors participating in the Physicians' Health Study, an ongoing study examining a variety of health issues.
Compared to doctors who had never smoked, those who smoked at least 20 cigarettes a day had about double the risk of developing cataracts, the researchers found.
'(These) data provide strong evidence that cigarette smoking is an independent risk factor for cataract,' the researchers wrote.
In the second study, another group of Harvard researchers examined 69,647 women participating in the Nurses' Health Study, a similar study examining women's health issues.
In this study, researchers found women who smoke or had smoked at least 35 cigarettes a day had a 60 percent increased risk for cataracts compared to those who had never smoked, the researchers said.
'Our study indicates that cigarette smoking increased the risk for cataracts requiring surgical extraction in women,' they said.
In an editorial accompanying the studies, West said the findings 'provide confirming evidence that smoking increases the risk of ... cataracts.' Based on the findings, West estimated one-fifth of all cataracts may be caused by smoking.
