ELEVATION OF TEAR FLUID PLASMIN ACTIVITY OF CONTACT-LENS WEARERS STUDIED WITH A RAPID FLUOROMETRIC ASSAY

Tear fluid plasmin activities were measured by a fluorometric assay ba sed on a lyophilized kit with the 7-amido-4-trifluoromethylcoumarin de rivate of the tripeptidyl H-D-Val-Leu-Lys as substrate. The rapid, sen sitive method can detect proteolytic activity in small volume tear flu id samples. Plasmin activity levels (IU/L) measured from the samples w ere corrected with tear fluid flows (mu l/min), yielding a parameter c alled plasmin flux (mu IU/min). Correction is important when patients show tearing due to irritation. Tear fluid samples were collected from 32 asymptomatic contact lens (CL) wearers and 27 controls. Plasmin ac tivity values (2.7 +/- 0.3 IU/L) of CL wearers were higher (p < 0.0000 6) than those of the controls (1.6-0.1). Mean plasmin flow was 12.6 +/ - 1.5 mu l/min for CL wearers and higher for controls (6.8 +/- 0.5 mu l/min). The difference was not significant (p = 0.063). Plasmin flux v alues of CL wearers (30.0 +/- 4.1 mu IU/min) were conspicuously higher than those of controls (10.2 +/- 0.7 mu IU/min, p < 0.00006). We conc lude that elevated tear fluid proteolytic activity may be related to p athological changes associated with CL wear.