An interesting study out of Japan this year examined tear production and related dry eye symptoms in two groups of patients: the first group was given caffeine and the second group was not.
Researchers found that the group taking 400 mg of caffeine (almost the equivalent of 4 cups of coffee) show significantly greater volume of ocular surface moisture than the group not taking the caffeine. While researchers proposed caffeine could be responsible for stimulating tear glands the same way it stimulates saliva and digestive juices, they were quick to point out further study is indicated before doctors start prescribing caffeine pills to their patients who suffer from dry eyes.
Of course, it's no surprise the caffeine group also indicated greater side effects such as increased heart rate, sweating, and nervousness. Although, some of these responses may be due to genetic variations that cause some patients to respond differently to caffeine intake.
While more research is indicated to understand the exact causes and the minimal amount needed to benefit ocular dryness, the bottom line is that morning cup of Joe may be helping to reduce the level of ocular surface dryness.
Dr. Beach
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