A new study out of Tokyo published in this month's American Journal of Ophthalmology (link here) reports that caffeine may improve tear film secretion. The true implication for dry eye treatment gleaned from this study's results are obviously in their infancy, but here is a breakdown of what researchers have found:
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| Pictured in blue is the layer of tear film that coats the surface of the eye, The tear film meniscus is the thickness of tears measured at the lower lid margin. In a patient without dry eye, the tear film meniscus would be greater than 2 mm. Picture courtesy University of Oxford |
78 participants were given either a placebo or a caffeine pill and their tear fear volume was measured afterwards. Apparently all users experienced increased tear production after consuming the caffeine pill. Tear film measurements increased on average between 0.06mm to 0.08mm. Consider that a patient with dry eye has a tear film meniscus (thickness of the tear film covering the eye) of less than 2 mm, even a small increase in tear volume may help relieve symptoms.
Caffeine has long been linked to increased saliva and digestive secretions, so an increase in tear gland secretion is not a surprise to researchers. The question is how can this information really be effectively utilized in improving patient comfort? Maybe someday we'll be seeing caffeine added to artificial tears?
Take for instance a lubricant like VIVA (which from previous posts you know I am quite fond of). Unlike your average OTC rewetting drop it contains a combination of supplements designed to mirror elements present in healthy, natural tears. That means no preservatives, vitamins (specifically Vitamin A) and natural growth factors. Now imagine adding a known secretagogue (a supplement known to improve tear gland secretion). Caffeine may be a natural answer, but we are far from any research in this area. The important point is there are so many new ways to treat dry eye, and we are only learning more all of the time!
