Leia o texto para responder à questão.
Smoking damages eyes as well as lungs
Millions of people in the UK are putting their sight at risk by continuing to smoke, warn specialists. Despite the clear connection, only one in five people recognise that smoking can lead to blindness, a poll for the Association of Optometrists (AOP) finds. Smokers are twice as likely to lose their sight compared with non-smokers.
That is because tobacco smoke can cause and worsen a number of eye conditions. Cigarette smoke contains toxic chemicals that can irritate and harm the eyes. For example, heavy metals, such as lead and copper, can collect in the lens - the transparent bit that sits behind the pupil and brings rays of light into focus - and lead to cataracts, where the lens becomes cloudy.
Smoking can make diabetes-related sight problems worse by damaging blood vessels at the back of the eye (the retina). In the poll of 2,006 adults, 18% correctly said that smoking increased the risk of blindness or sight loss, while three-quarters (76%) knew smoking was linked to cancer. The AOP says stopping or avoiding smoking is one of the best steps you can take to protect your vision, along with having regular sight checks.
(www.bbc.com, 02.07.2019. Adaptado.)
In the excerpt from the third paragraph “one of the best steps you can take”, the underlined word expresses