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M Senchyna, LW Jones, D Louie, I Forbes, C May; Optimization of Methodologies to Characterize Lysozyme Deposition Found on Balafilcon and Etafilcon Contact Lens Materials . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3082.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: We sought to (1) develop and optimize efficient and accurate methods to extract and characterize lysozyme deposits found on both balafilcon and etafilcon contact lens materials; (2) determine whether differences in lysozyme deposition and activity exist following lens care with a polyquad-based system (OptiFree®Express®, Alcon Laboratories) versus a polyhexanide-based system (ReNu® MultiPlus®, Bausch and Lomb). Methods: Deposit extraction was performed in either an SDS-based or an acid-based solution. Efficiency of each extraction protocol was evaluated by spectrophotometry. Following extraction, total protein was measured using a Micro-BCA assay. Lysozyme concentration in each extract was determined via SDS-PAGE electrophoresis and Western blotting. Lysozyme activity was determined by the rate of lysis of Micrococcus lysodeikticus cells. Results: Comparison of the two extraction methods demonstrated that the acid-based solution was significantly more efficient with respect to lysozyme removal compared to the SDS-based solution. Following acid-based extraction, evaluation of the effect of varying lens care regimens revealed that both total protein and lysozyme deposited on etafilcon lenses was greater following lens disinfection with ReNu® MultiPlus® compared to disinfection with OptiFree® Express® (total protein: 2005 252 vs 1413 247 (p<0.001); lysozyme: 1551 371 vs 935 271 (p<0.001)µg/lens). In the case of balafilcon lenses, lens care regimen did not significantly affect the amount of lysozyme deposited (p=NS). For both lens materials, the levels of denatured lysozyme measured following care with ReNu® MultiPlus® was greater than that seen on lenses disinfected with OptiFree® Express® (28 vs 21% for etafilcon lenses; p=0.053 and 57 vs 40% for balafilcon lenses; p=0.04). Conclusions: We have optimized both extraction and quantification methodologies to facilitate the accurate characterization of lysozyme deposition and activity on both traditional and novel silicone-hydrogel contact lens materials. Utilizing these procedures, we have demonstrated that lysozyme deposition (quantity and conformation) is significantly influenced by both lens material and care regimen.
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