Schirmer's test. A closer look.

In 50 normal subjects, results of kinetics studies of Schirmer's test demonstrated nonlinear wetting with an initial rapid phase of wetting followed by a progressive reduction in rate. This initial rapid phase of wetting indicated a reflex secretion of tears. In the majority of subjects, topical anesthesia with 0.5% proparacaine hydrochloride dampened the initial reflex secretion but could not completely suppress it. The data indicated that Schirmer's test with anesthesia was not capable of measuring a basic tear secretion independent of reflex components.