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Curtis B. Dobson, Philip B. Morgan, Carole Maldonado-Codina, Karl A. Payne; Effect of Contact Lens Solutions on the Structural and Functional Integrity of Lens Bound Tear Proteins. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6536.
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Proteins within tears, including lysozyme, accumulate on and within soft contact lenses during wear. Although the presence of denatured protein deposits can result in reduced vision, discomfort and clinical complications for the contact lens wearer, it has been proposed that denaturation may additionally lead to loss of beneficial function including antimicrobial activity. We therefore investigated the direct antimicrobial activity of proteins extracted from ex vivo lenses and the effect of treatment of lenses with different contact lens solutions on the functional and structural integrity of these proteins.
Worn and unworn hydrogel soft contact lenses were treated overnight with either a hydrogen peroxide-based cleaning solution (Oxysept 1 step) or an investigational formulation of Biotrue multipurpose solution (MPS), prior to tear protein extraction with ACN/TFA. The structural integrity of lysozyme from worn lenses was assessed by standard methods, measuring its rapid lytic activity against Micrococcus luteus. In addition, the functional integrity of the extracted lens proteins was tested by challenging suspensions of Pseudomonas aeruginosa (ATCC 9027) and Staphylococcus aureus (ATCC 6538) overnight, and assessing numbers of surviving organisms by colony counting.
Extracts from worn lenses comprised mostly lysozyme (this was confirmed by Western blotting). Incubation with extracts resulted in a 2 to 3 log decrease in cell viability relative to that for extracts from unworn lenses. This activity was maintained when incubated overnight with the MPS, but was strongly inhibited when incubated with the peroxide-based lens solution.
These data strongly suggest that tear proteins absorbed to soft contact lenses possess potent antimicrobial activity that most likely involves direct inhibitory activity of lysozyme, and possibly activity of other less abundant antimicrobial proteins or peptides. The activity is maintained after exposure to the MPS but inhibited after exposure to the hydrogen peroxide solution.
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