By Adrian Galbreth
The regular intake of caffeine can help to reduce the chances of people suffering from dry eye syndrome, it has been claimed.
A new study by researchers at the University of Tokyo's School of Medicine shows that caffeine intake can significantly increase the eye's ability to produce tears, which could lead to major new developments in the treatment of dry eyes.
The condition affects around five million people in the UK at some point in their life and can cause significant discomfort, and can even escalate into a vision-threatening disease.
It involves malfunction of the rate of tear production, the quality of tears and the rate of evaporation from the surface of the eye, with can including gritty, scratchy or burning sensations, excessive tearing, and the production of stringy mucus.
In the study, which was published in Ophthalmology, the journal of the American Academy of Ophthalmology, all 78 participants produced significantly more tears after consuming caffeine than after taking a placebo.
The research was led by Dr Reiko Arita, who was inspired by an earlier study in which only 13 per cent of caffeine users were found to have dry eye syndrome, compared with 17 per cent of non-users.
Although the experts knew that caffeine was likely to stimulate tear glands, since it is known to increase other secretions, and that people respond differently to caffeine, they analysed study participants' DNA samples for two genetic variations that play important roles in caffeine metabolism.
Even taking these into account, tear production proved to be higher in study subjects who had the two genetic variations.
Dr Arita explained: "If confirmed by other studies, our findings on caffeine should be useful in treating dry eye syndrome. At this point, though, we would advise using it selectively for patients who are most sensitive to caffeine's stimulating effects."
by Martin Burns