In vitro adhesion of Acanthamoeba castellanii to soft contact lenses depends on water content and disinfection procedure

Purpose To compare the potential of different soft contact lenses to be contaminated with Acanthamoeba castellanii as a function of material parameters and cleaning procedures. Methods Different unworn soft hydrogel and silicone hydrogel contact lenses were incubated with human pathogenic A. castellanii . The adhesion of the acanthamoebae was investigated on the contact lenses and put into relation to their material parameters. The efficacy of a recommended contact lens cleaning procedure in reducing A. castellanii adhesion was investigated. Results We found that material parameters such as elastic modulus, silicone content, ionic properties and swelling do not influence the adhesion of acanthamoebae to soft contact lenses. A material parameter that influenced adhesion significantly was the water content of the lens. With increasing water content, the adhesion of acanthamoebae increased. By following the cleaning instructions of the manufacturer the contamination of the lenses with A. castellanii could be reduced to a minimum, as shown both on contact lenses and in control experiments. Conclusion With this study we show that for the tested lenses, the adhesion of A. castellanii to contact lenses is independent of the silicone content of the lens, but depends nonlinearly on the water content of the lens. Furthermore, we demonstrate that applying proper lens cleaning procedures minimizes the risk of acanthamoebae adhesion to contact lenses.