Two studies in the Journal of the American Medical Association published yesterday say that smoking doubles the risk in men and increases it by more than one and a half times in women.
In the first report Dr William Christen, Department of Medicine, Harvard Medical School, reports on a five-year study of 17,842 male doctors aged 40 to 84.
At the start of the study 10 per cent were smokers, 39 per cent were past smokers and 51 per cent had never smoked. 'Compared with never smokers, current smokers had approximately twice the risk of cataract,' he says. Past smokers were also more likely to develop cataract, though the difference was less pronounced.
The women's study is a continuing project and involves a group of nearly 70,000 nurses whose health is being monitored. 'We observed a statistically significant trend over increasing categories of smoking exposure,' Susan Hankison, of the Department of Medicine at Harvard, says.
A leading article in the journal says that smoking may be the cause of one in five cases of cataracts in the American population. While saying that more work is needed to discover how smoking damages the lens of the eye it adds: 'For now 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.'
Cataracts are a very common disease of the lens of the eye, which becomes opaque. It is primarily a condition in elderly people. By the age of 75 most people have cataracts sufficiently developed to impair their vision.