Caffeine intake, in general, does not seem to increase risk of DED. Photo: Nathan Dumlao on Unsplash.

One of the most common complaints optometrists hear from patients in their chairs is “my eyes are dry.” Dry eye is a multifactorial condition affecting between 5% and 50% of people, and as such, research that investigates the various risk factors for this disease is critical and will aid in slowing its increasing prevalence. A study recently looked into the world’s most consumed bioactive substance, caffeine, and its potential correlation to DED. Good news, coffee enthusiasts: the data showed that caffeine intake is not a risk factor for DED in the majority of the population.

The study included 85,302 participants (59% female, average age: 51) who took the Women’s Health Study dry eye questionnaire. Caffeine intake was calculated from four commonly consumed beverages: coffee, tea, cola and energy drinks. Other potential sources of caffeine, including chocolate and caffeine pills, were not accounted for in this study.

The average daily caffeine intake was 285mg. The researchers found that after correcting for demographics, body mass index, smoking status and alcohol intake, higher caffeine intake was associated with a decreased risk of DED as evaluated by the questionnaire (OR of 0.97 per 100mg/day). The effect was similar between males and females and was not affected by medical comorbidities, reported sleep quality or stress level. In addition, decaffeinated coffee was found to be associated with an increased risk of DED (OR of 1.05 per cup/day).

The data did show that after adjusting for all comorbidities, increased caffeine intake was linked to highly symptomatic dry eye but a decreased risk of DED diagnosis, which the researchers noted supports the results of previous studies.

“It is possible that caffeine affects dry eye symptoms separately from tear secretion and ocular surface parameters,” the researchers wrote in their paper. “Caffeine may also have direct ocular effects and seems to overall stimulate lacrimal gland secretion.” They added that because caffeine is a diuretic, some have speculated it may trigger DED through dehydration, but normal consumption has been proven not to have a significant diuretic effect.

Overall, results of this study support that in the general population, dietary caffeine intake doesn’t appear to be associated with DED development.