Effects of the Schirmer test on the fibrinolytic system in the tear fluid.

Human tear fluid was collected with blunted glass capillaries before and after performing the Schirmer test (ST). The test caused an increase in the tear fluid (TF) plasmin concentration (from 0.40 +/- 0.29 microgram ml-1 (mean +/- S.E.M.) to 1.14 +/- 0.26 microgram ml-1; Mann-Whitney test P less than 0.001) and a decrease in plasminogen activator activity (from 2.04 +/- 0.24 IU ml-1 to 1.04 +/- 0.17 IU ml-1; Mann-Whitney test P less than 0.002). In the filter paper used for ST, that segment that had been in contact with the conjunctiva (5 mm) usually contained higher amounts of plasmin than the following 5 mm of the paper overhanging the lidmargin. The present results indicate that the TF collection may affect the plasminogen activator-plasmin system in TF, depending on the collection method used.