• 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.
Clinch TE, Benedetto DA, Felberg NT, Laibson PR. Schirmer's TestA Closer Look. Arch Ophthalmol. 1983;101(9):1383-1386. doi:10.1001/archopht.1983.01040020385009