Passive smoking increases the risk of one of the most common causes of blindness, a study has found.
About 500,000 people in the UK have AMD
A Cambridge University team looked at the impact of smoking on age-related macular degeneration (AMD), the British Journal of Ophthalmology reported.
Living with a smoker for five years doubled the risk of the disease and regular smoking tripled it, they found.
Campaigners said it highlighted the need for an outright ban on smoking in enclosed public places and workplaces.
Research has already shown that smoking increases the risk of vision problems, but this study has presented the clearest evidence yet that passive smoking can have a similar impact.
AMD usually develops after a person reaches the age of 50.
It affects the central part of the retina, key for reading and driving, leaving only peripheral vision intact. It does not always lead to blindness.
There are about 500,000 people in the UK with AMD.
The researchers studied 435 people with AMD and 280 people without, looking at their smoking habits and the development of disease.
They found the more a person smoked the greater the risk of them and their partners developing AMD.
Regularly smoking a pack of cigarettes or more a day for 40 years almost tripled the risk, while living with a smoker for at least five years doubled it.
However, they found for people who had given up smoking for 20 years or more the risk was cut to levels comparable to non-smokers.
Report co-author Professor John Yates said the researchers had "demonstrated a clear association" between smoking and the disease.
"Of the many environmental factors investigated in relation to AMD, smoking is the one most consistently found to be associated with increased risk."
Anita Lightstone, the Royal National Institute of the Blind's head of eye health, said: "This is an extremely important finding and further evidence to back RNIB's call for a ban on smoking in all enclosed public places and workplaces across the UK."
The government has proposed a ban on smoking in England in all workplaces, with the exception of pubs which do not serve food and private members' clubs.