Blindness & Smoking
Published on January 11, 2010 6:54 AM
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Many smokers are not aware of the danger of the link between tobacco smoking and blindness. For example, US researchers found recently that even after the age of 80, smoking raised a person's risk of developing age-related macular degeneration (AMD), the leading cause of blindness among Americans aged 65 and over, meaning it is never too late to give up the habit.
AMD causes a darkening and blurring of central vision, and prevents smokers from being able to read, drive or recognize people. 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.
Statistics show that AMD affects about 1.75 million Americans and this figure is expected to rise to just under 3 million by 2020. The second most common dangerous factor for AMD is smoking because age is the first.
The recent research was conducted by Dr. Anne Coleman, professor of ophthalmology at the Jules Stein Eye Institute at University of California, and her colleagues which wanted to find out if the age can be linked to the effect of smoking on AMD risk.
At the end of the investigation they found 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. This research provides the first exact 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 relapse 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 also found that in general the smokers had 11 percent 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.
Meditating 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 lowering the amount of pigmentation in the retina.
