The syndrome is not only a nuisance for many, but it can affect vision. Researchers at the University of Tokyo’s School of Medicine found that all of the 78 people under the study after using caffeine produce considerably more tears than those who took placebo.
Women are the major victim of dry eye, though it is not uncommon in men. Symptoms can include gritty, scratchy or burning sensations, excessive tearing, and/or production of stringy mucus.
The research team was motivated by an earlier study which had concluded a reduced risk for the syndrome in caffeine users: 13 per cent of users had dry eye in comparison with nearly 17 per cent of non-users.
The team 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.
Tear production proved to be higher in study subjects who had the two genetic variations.
“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,” said Dr. Reiko Arita, the research head.
The study has been published in Ophthalmology, the journal of the American Academy of Ophthalmology.