Aspects of Tear Fluid Composition in Hydrogel Contact Lens Wear

Abstract

This study was designed to investigate the interactions of hydrogel contact lenses and the levels of proteins within the pre-ocular tear film (P.0.T.F.). Firstly it was necessary to establish a standardised technique for the qualitative and quantitative assessment of these lacrimal proteins. This was achieved using polyacrylamide gel electrophoresis, incorporating Sodium Dodecyl sulfate (S.D.S.), to raise the sensitivity level of the technique. After the electrophoresis had been completed the gels were stained for protein fractions using Coomassie Brilliant Blue and qualitative results obtained using a densitometer. A "waking hours" study was undertaken to assess any circadian relationship which could influence the -experimental design of the hydrogel lens studies. No such time-linked variation was established with the lacrimal protein levels of non-contact lens wearers. Thus four groups were designed, one group being a control. All groups contained ten adult male volunteer subjects. Each of the three contact lens groups were fitted using different water content hydrogels:- (a) Bausch & Lomb Soflens, (b) Sauflon 85 and (c) Sauflon 70. Both (a) and (c) are daily wear lenses and (b) is an extended wear lens. A 5µl sample of tears was taken from each subject at pre-determined data collection points throughout a twelve week period.  Using an analysis of variance technique the results showed that all three types of hydrogels were related to a significant change in the tear protein profiles. Trends in both the total, and individual amounts of protein, such as albumin, globulin and lysozyme were monitored. Over the initial stages of adaptation to contact lenses wear, a sharp decrease in the total amount of protein was ‘observed. This was followed by the establishment of more stable values towards the final eight weeks of each study. A more complex response was obtained for the individual sub-groups of proteins.