Tear Protein Composition and Contact Lens Wear

Abstract

Tear Protein composition has been extensively investigated since lysozyme, one of its major components, was discovered by Fleming in 1922. Much of the current interest lies with the analysis of its components and their interaction with the contact lens during wear. Because of the limit volume of tear fluids, some of its components are not readily accessible for analysis. Recent developments in micro-electrophoresis and immunochemistry have enabled the identification, characterization and quantification of proteins found in tears. The use of hydrogels in contact lens wear have been plagued with problems associated with proteinaceous deposits and chemical preservatives which appear to provoke an adverse eye reaction. The aetiology of which may be immunologic and/or toxic. Preservatives such as Thimerosal and Chlorhexidine appear to bind or complex with the denatured protein on the lens. These preservatives concentrate and are later released onto the eye to precipitate a toxic reaction. In addition the preservatives may inhibit the four principal proteins - Lysozyme, Lactoferrin, Specific tear prealbumin and IgA, that play a protective role against infection. A 24 week group comparative study was initiated to investigate changes in tear protein composition with hydrogel lens wear and its associated care regimen. Acrylamide gel electrophoresis was used to look at the distribution of the total protein profile while immunoelectrophoresis was employed to quantify lysozyme and IgA levels among four groups of subjects. In general, it was found that there was not significant difference among the groups in the total protein, lysozyme and IgA (secretory) levels over the period of 24 weeks(p=0.0001). Also there was no significant difference in protein profiles among the Group with respect to time (p=0.0001). However, there was a gradual increase in protein content with time which may be due to seasonal changes.