Passive smoking almost doubles the risk of the progressively degenerative eye disease, age related macular degeneration, shows research, published in the British Journal of Ophthalmology.
The macula is crucial for fine central vision, which is essential for tasks, such as reading and driving.
The risk of macular degeneration increases once someone is over the age of 60. It is a leading cause of partial sightedness and blindness in many European countries and the USA.
The researchers base their findings on 435 people with end stage macular degeneration and 280 partners who lived with them.
They found that the more a person smoked, the greater were their chances of developing age related macular degeneration, and the results showed that it was the amount smoked rather than whether someone had ever smoked that was critical.
Regularly smoking a pack or more a day for 40 years almost tripled the risk of age related macular degeneration compared with those who did not smoke, the research showed.
Smoking increased the risk of both types of macular degeneration ( geographic atrophy and choroidal neovascularisation ).
Giving up for 20 years or more cut the risk to levels comparable with those for non-smokers, the research found.
The risks were also increased for partners who were non-smokers, and had lived with a smoker for five years or more. Their risk nearly doubled.
Source: British Medical Journal, 2005