The effect of caffeine on tear formation

The effect of caffeine on tear formation of thirty young healthy subjects (mean age: 22.27±2.7yrs), was studied using Schirmer test 1. The Pre-test, post-test method of experimental design was used. The tear formation was evaluated before and after intake of 150ml cup of coffee (caffeine concentration of 1.65g/l derived by dissolving a teaspoon of pure coffee in 150ml of water). The post-test was at hourly intervals over a periodof four hours.A reduction in tear formation from the mean baseline value (22.5mm) was recorded after the hourly intervals thus 19.67mm, 13.73mm, 15.50mmand 16.18mmat 1hr, 2hrs 3hrs and 4hrs respectively. This showed a percentage reduction of 12.58%, 38.98%, 31.11% and 28.09% respectively. The greatest reduction was therefore recorded 2hrs after intake of caffeine. This effect was significant (P>0.05) using the paired t-test. It may be necessary to advise patients with symptoms of dry eye to avoid caffeinated substances so as not to aggravate their condition.