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Tear plasmin activity with contact lens wear
A Vannas1, D F Sweeney, B A Holden
1Cornea and Contact Lens Research Unit, School of Optometry, University of New South Wales, Sydney, Australia.
Current Eye Research
|March 1, 1992
Summary
Tear plasmin activity, an enzyme linked to ocular issues, increases with extended contact lens wear. This rise is primarily due to eye closure, not the lens material or oxygen levels.
Area of Science:
- Ophthalmology
- Biochemistry
- Tear Film Research
Background:
- Plasmin, a proteolytic enzyme, is found in tears of patients with anterior ocular disease and during contact lens wear.
- Elevated plasmin levels may indicate ocular surface stress or inflammation.
Purpose of the Study:
- To investigate the relationship between contact lens wear (soft and rigid, daily and extended wear) and tear plasmin activity.
- To determine if eye closure or lens-induced hypoxia contributes to increased plasmin levels.
Main Methods:
- Radial caseinolysis procedure used to quantify tear plasmin activity.
- Tear samples analyzed from 66 contact lens wearers and non-wearers.
- Tear plasmin levels assessed after varying durations of eye closure and contact lens wear.
Main Results:
- Extended wear of soft and rigid contact lenses was significantly associated with higher tear plasmin activity compared to non-wearers.
- Eight hours of open-eye wear of thick HEMA lenses did not induce plasmin activity.
- Significant increases in tear plasmin activity were observed after 1-hour and overnight eye closure, with or without lenses.
- Overnight eye closure also increased epithelial cells and leucocytes in tear fluid.
Conclusions:
- Increased tear plasmin activity during extended contact lens wear is likely caused by eye closure effects.
- Hypoxia or the contact lens material itself may not be the primary drivers of elevated plasmin.
- Eye closure appears to be a significant factor influencing tear enzyme activity in contact lens wearers.