Plasmin and epidermal growth factor in the tear fluid of contact-lens wearers: effect of wearing different types of contact lenses and association with clinical findings

Abstract

The concentrations of plasmin and epidermal growth factor were determined in tear fluid (TF) samples from wearers of different types of contact lenses (CLs) during and after cessation of CL wear (CLW). TF samples of 50 healthy eyes served as controls. The plasmin concentrations in the control group (0.4 +/- 0.1 microgram/ml; mean +/- SEM) were significantly lower (p less than 0.001) than in the group of soft CL (SCL) wearers during CLW (1.2 +/- 0.2 microgram/ml). Cessation of CLW led to a decrease in TF plasmin concentrations from 1.2 +/- 0.2 to 0.6 +/- 0.1 micrograms/ml in the group of SCL wearers (p less than 0.001), from 1.5 +/- 1.1 to 0.3 +/- 0.2 micrograms/ml in the group of extended-wear SCL wearers (p greater than 0.05) and from 0.4 +/- 0.3 to 0.0 +/- 0.0 microgram/ml in the group of gas-permeable CL wearers (p greater than 0.05). After CLW cessation, TF plasmin levels of CL wearers did not differ from those of controls. The occurrence of plasmin in TF was associated with a higher degree of corneal neovascularization and with the presence of limbal injection. The concentrations of epidermal growth factor in TF were not significantly altered by the discontinuation of CLW.