Several local scientists have found additional evidence in test tube studies for an already widely reported association between smoking and eye disease.

Six researchers from a local institute of the Chinese Academy of Sciences, supported by U.S. colleagues, have collected evidence suggesting that acrolein, an ingredient in tobacco, can lead to blindness.

"Smoking and passive smoking will gradually blur people's eyesight," said Liu Zhongbo, a researcher in the city's Institute for Nutritional Sciences.

The researchers ran tests on human retinal cells and their mitochondria - which provide energy for cells. By applying acrolein to the cells, the researchers recorded different levels of damage on the retinal cells depending on the acrolein concentration.

The laboratory research, which did not involve human or animal studies, adds another piece to an accumulating body of evidence suggesting that acrolein can promote age-related macular degeneration (AMD) - a blindness-causing eye disease.

AMD is the most common cause of vision loss for people over the age of 55 in Europe Union, experts said.

"Our tests showed that smoking was a slow killer of eyes," said Liu, noting that high concentrations of acrolein immediately disable the cells.

It wasn't clear, however, whether the level of acrolein exposure in the study bore any relationship to the exposure that smokers would encounter in their routine smoking habit.

According to a UN statistics, worldwide, there are 20 to 25 million new cases of AMD every year. In half the cases, the disease leads to blindness.

However, belief in a link between smoking and blindness has not been universally accepted.

Hu Jinhua, secretary-general of Shanghai Smoking and Health Association, said smoking is very harmful to the lungs but he was not convinced by the study that smoking might lead to blindness.

(Shanghai Daily September 21, 2006)