People who smoke are twice as likely to have age related macular degeneration (AMD), a leading cause of blindness in the elderly, as those don't, according to a study of more than 4,000 Britons aged 75 years.

"Smoking is associated with a twofold increased risk of developing AMD," said Professor Astrid Fletcher, of the London School of Hygiene and Tropical Medicine, in a study published in the British Journal of Ophthalmology. 

AMD is an illness that blurs the central vision. It affects the macula, or part of the eye that sees fine detail. In the United States alone it afflicts about 10 million to 15 million people.

The risk of suffering from the illness increases with age.

(Xinhua News Agency/Agencies April 14, 2005)