US
researchers found that even after the age of 80, smoking increased a person's
risk of developing AMD, age-related macular degeneration, the leading cause of
blindness among Americans aged 65 and over, suggesting it is never too late to
give up the habit.
The study was the work of lead author Dr Anne Coleman, professor of
ophthalmology at the Jules Stein Eye Institute at University of California, Los
Angeles (UCLA), and colleagues, and is published in the January issue of the
American Journal of Ophthalmology.
AMD causes a darkening and/or blurring of central vision, and prevents you from
being able to read, drive and recognize people you know. It is a progressive
degeneration of the macula, the centre of the retina, the part of the membrane
inside the back of the eye that allows us to see fine details.
Advanced AMD with loss of vision affects about 1.75 million Americans: this
figure is expected to rise to just under 3 million by 2020.
Smoking is the second most common risk factor for AMD: age is the first. Coleman
and colleagues wanted to find out whether age was linked to the effect of
smoking on AMD risk.
Coleman told the press that age was the strongest predictor for AMD, yet most of
the research done on the disease only looked at people aged 75 and under.
"Our population was considerably older than those previously studied," said
Coleman.
"This research provides the first accurate snapshot of how smoking affects AMD
risk later in life," she added.
For the study, Coleman and her team compared the retinal photographs of nearly
2,000 women taken at age 78 and 83, looked for signs of AMD and then did
logistical regression statistical tests to find out whether smoking affected the
women's risk of developing the disease.
The women were already taking part in a study called the Study of Osteoporotic
Fractures, where 45 degree stereoscopic fundus retinal photographs were part of
the observations taken at clinic follow ups in year 10 and 15 of the study.
They found that:
* Overall, the smokers had 11 per cent higher rates of AMD than the non-smokers
of the same age.
* But among the over 80s, the smokers were 5.5 times more likely to develop AMD
than the non-smokers.
The authors concluded that:
"The magnitude of the greater-than-additive effect of smoking on the
age-adjusted risk of AMD reinforces recommendations to quit smoking even for
older individuals."
"The take-home message is that it's never too late to quit smoking," said
Coleman.
"We found that even older people's eyes will benefit from kicking the habit,"
she added.
Speculating on the underlying biological reasons for this link, the authors said
there is a theory that smoking increases AMD risk by reducing levels of
antioxidants in the blood, changing the blood flow to the eyes and reducing the
amount of pigmentation in the retina.
Dr Paul Sieving, director of the National Eye Institute, which funded the
research with the National Institute on Aging, said this study gives:
"Yet another compelling reason to stop smoking and suggests that it is never too
late to quit."
Source : Medical News Today
