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 based on a lyophilized kit with the 7-amido-4-trifluoromethylcoumarin derivative of the tripeptidyl H-D-Val-Leu-Lys as substrate. The rapid, sensitive method can detect proteolytic activity in small volume tear fluid samples. Plasmin activity levels (IU/L) measured from the samples were corrected with tear fluid flows (microliters/min), yielding a parameter called plasmin flux (microIU/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 activity values (2.7 +/- 0.3 IU/L) of CL wearers were higher (p < 0.00006) than those of the controls (1.6-0.1). Mean plasmin flow was 12.6 +/- 1.5 microliters/min for CL wearers and higher for controls (6.8 +/- 0.5 microliters/min). The difference was not significant (p = 0.063). Plasmin flux values of CL wearers (30.0 +/- 4.1 microIU/min) were conspicuously higher than those of controls (10.2 +/- 0.7 microIU/min, p < 0.00006). We conclude that elevated tear fluid proteolytic activity may be related to pathological changes associated with CL wear.
University Eye Hospital, University of Helsinki, Finland.
T
T
Virtanen
N
N
Honkanen
M
M
Härkönen
A
A
Tarkkanen
T
T
Tervo
D003263:Contact Lenses, Hydrophilic; D005341:Fibrinolysin / Q000378:metabolism*; D005470:Fluorometry / Q000379:methods; D006801:Humans; D013666:Tears / Q000201:enzymology* / Q000378:metabolism
D005341:Fibrinolysin