Tokyo, Apr 19 (IANS): Caffeine intake may help overcome dry eye syndrome (DES) -- caused by the diminishing ability to produce tears with symptoms like grittiness, scratchy or smarting sensation and production of stringy discharge from the eyes -- reveals a study.

The disease, for many, could simply be annoying, but for others it could lead to the loss of vision. DES affects about four million people aged 50 and above in the US alone.

Researchers led by Reiko Arita, from the University of Tokyo's School of Medicine, conducted tests on 78 participants, who produced significantly more tears after consuming caffeine than after taking a placebo, the journal Ophthalmology reported.

The research was inspired by an earlier study that had shown a reduced risk for dry eye in caffeine users: 13 percent of users had the syndrome compared to nearly 17 percent of non-users, according to a Tokyo statement.

The team knew that caffeine was likely to stimulate tear glands, as it was known to increase other secretions, such as saliva and digestive juices. They also knew that people respond differently to caffeine, so they analysed study participants' DNA samples for two genetic variations that play important roles in caffeine metabolism, the university said.

Tear production proved to be higher in participants who had two genetic variations.

"If confirmed by other studies, our findings on caffeine should be useful in treating dry eye syndrome," said Arita. "At this point, though, we will advise using it selectively for patients who are most sensitive to caffeine's stimulating effects."