A new in vitro method for assessing the potential toxicity of soft contact lens care solutions

We describe a method for determining the cytotoxic effect of soft contact lens care solutions. The method provides a means for the direct exposure of mammalian cells to solutions and to lenses that have been soaked in solutions. Cytotoxicity was indicated by significant increases in the number of dead cells relative to controls. The cytotoxicity of a test battery of eight compounds was determined, particularly benzalkonium chloride (BAK). In addition, nine commercial soft contact lens care products containing a variety of preserving/disinfecting agents were also examined. A modification of the basic assay for assessing the kinetics of toxicity is also described. The results indicate that this new method is useful for identifying compounds that bind to soft contact lenses, such as BAK, and induce cytotoxicity and others that should be rinsed from lenses or neutralized (such as hydrogen peroxide) to minimize the potential for irritation.