Analysis of bacterial transmission in contact lens wear and care

PhD ceremony: Ms. W. Qu, 14.30 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Analysis of bacterial transmission in contact lens wear and care

Promotor(s): prof. H.C. van der Mei, prof. J.M.M. Hooymans, prof. H.J. Busscher

Faculty: Medical Sciences

Microbial keratitis is a serious complication of wearing contact lenses and can lead to serious visual impairment. Bacterial adhesion to contact lenses is one of the crucial steps in microbial keratitis, which can be regarded as a transmission phenomenon of pathogenic organisms from contact lens case to contact lens to cornea. The aim of this thesis is to develop a method to predict bacterial transmission probabilities based on adhesion force comparisons and to investigate the surface thermodynamic basis for bacterial transmission. Whether or not transmission occurs, depends on the relative magnitude of adhesion forces between causative bacteria with donating lens case and receiving contact lens surface. We first investigated the adhesion forces of bacteria isolated from keratitis to lens case, contact lens and cornea surfaces using Atomic Force Microscopy (AFM), and applied a Weibull analysis on these forces to calculate bacterial transmission probabilities from lens case to cornea with a contact lens as an intermediate. Calculated transmission probabilities coincided well with experimental data, and were in line with surface thermodynamic principles. In addition, preventive measures for the development of contact lens-related infections were analyzed from the transmission perspective, including the influence of Ag-coatings and an anti-adhesive VitroStealth® coating on contact lens cases. Weak adhesion forces and severe bacterial killing were found on Ag-impregnated and VitroStealth® - coated lens cases. These coatings demonstrated to be effective in discouraging microbial adhesion and simultaneously imply better cleaning ability.