I'm not usually a big fan of caffeine, but this is interesting ...
"This common eye condition, caused by the inability of the eye to produce enough tears or increased evaporation of tears from the eye surface, affects about four million people age 50 and older in the United States. For many, dry eye syndrome is simply uncomfortable and annoying, but for others it escalates into a vision-threatening disease. Current treatment options range from simple warm compresses, eye washes and artificial tears to medications and tear drainage devices.
Dr. Reiko Arita of the University of Tokyo School of Medicine was motivated to pursue this study based on a previous study reporting that caffeine users had a lower risk of dry eyes than non-caffeine users: 13 percent of users had dry eye in comparison with nearly 17 percent of non-users.
Apart from knowing that caffeine increases the secretion of saliva and digestive juices, the team was also aware that individuals respond differently to caffeine. The team analyzed DNA samples of the participants for two genetic variations which are known to play a role in metabolizing caffeine.
In the new study published in the journal Ophthalmology, the team showed that participants with genetic variations in the ADORA2A and CYP1A2 genes had greater tear production after caffeine consumption." http://www.asianscientist.com/health-medicine/caffeine-coffee-relief-for-dry-eye-syndrome-2012/
I wish I had those genes. I drink coffee everyday...and still have chronic dry eyes. It may also be because I have VERY horrible (nearsighted) vision and my eyes just suck in every way possible.