[On the antimicrobial activity of benzalkonium chloride in potential contact lens fluids].

To assess the suitability of benzalkonium chloride as a preserving agent for potential contact lens fluids, the authors tested its antimicrobial efficiency at various pH values, in the presence of viscosity modifiers (hydroxyethylcellulose, polyvinylpyrrolidone, polyacrylamide) and also in combination with other preserving agents. The diffusion test and the suspension test were used as test methods. The efficiency of benzalkonium chloride depends upon the pH value of the solution and upon the concentrations of the viscosity modifiers. No better results were achieved by combination with phenylethanol and chlorobutanol. Formulations for potential contact lens fluids were indicated, the appropiateness of which is viewed in microbiological perspective.