https://orcid.org/0000-0002-2107-985X
Dear editor
We thank Professors Chaurasiya, Khurana, and Soni for their letter regarding our recent publication demonstrating lens solution-dependent stabilization of tear lysozyme. As they note, this in vitro study does not account for all the interactions that occur in the eye during contact lens wear. Contact lens researchers, including manufacturers, frequently rely upon in vitro studies to understand interactions of elements, mechanisms of action and contributions to product safety and efficacy. Our study is not meant as a substitute for clinical studies; it is to identify interactions and mechanisms that can occur during lens wear worthy of further investigation.
As discussed in the article, we chose lysozyme as a model tear protein due to its abundance in natural tears,Citation1 its antimicrobial properties,Citation2 its tendency to deposit on soft contact lenses clinically,Citation3 and the existence of an established assay that indicates the sorbed protein’s conformational state.Citation4 While interactions between the various components present in the tear film during lens wear and lysozyme undoubtably affect its stability, a collection of studies from the Centre for Contact Lens Research at the University of Waterloo provides evidence that changes in the activity of lysozyme sorbed on contact lenses in vitroCitation2,Citation4,Citation5 are also observed clinically during lens wear.Citation2,Citation3,Citation6 Proteins other than lysozyme are also vulnerable to denaturation when exposed to denaturing conditions such as detergents or sorption on a lens, and this may lead to corneal inflammation and discomfort. Laboratory investigations to establish the influence of protein interactions and mechanisms on contact lens deposition continue to be relevant for understanding clinical performance.
Disclosure
The authors declare no additional conflicts of interest regarding this communication beyond those disclosed in the original publication.
References
- Tiffany JM. Tears in health and disease. Eye. 2003;17(8):923–926. doi:10.1038/sj.eye.6700566
- Omali NB, Subbaraman LN, Coles-Brennan C, Fadli Z, Jones LW. Biological and clinical implications of lysozyme deposition on soft contact lenses. Optom Vis Sci. 2015;92(7):750–757. doi:10.1097/OPX.0000000000000615
- Heynen M, Ng A, Martell E, Subbaraman LN, Jones L. Activity of deposited lysozyme on contemporary soft contact lenses exposed to differing lens care systems. Clin Ophthalmol. 2021;15:1727–1733. doi:10.2147/OPTH.S296116
- Hall B, Jones L, Forrest JA. Measuring the kinetics and activity of adsorbed proteins: in vitro lysozyme deposited onto hydrogel contact lenses over short time periods. J Biomed Mater Res A. 2013;101(3):755–764. doi:10.1002/jbm.a.34357
- Subbaraman LN, Jones L. Kinetics of lysozyme activity recovered from conventional and silicone hydrogel contact lens materials. J Biomater Sci Polym Ed. 2010;21(3):343–358. doi:10.1163/156856209X415873
- Subbaraman LN, Glasier MA, Varikooty J, Srinivasan S, Jones L. Protein deposition and clinical symptoms in daily wear of etafilcon lenses. Optom Vis Sci. 2012;89(10):1450–1459. doi:10.1097/OPX.0b013e318269e583