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Purpose: There has been increasing awareness of the need for more powerful contact lens disinfectants, ideally having low toxicity and allergenicity to ocular tissue. Opti-Free Express with ALDOX Multi-Purpose Disinfecting Solution (MPDS) was recently marketed as a new multi-purpose disinfecting solution for soft contact lenses. MPDS contains two antimicrobial agents, polyquaternium-1 and myristamidopropyl dimethylamine, to broaden the range of antimicrobial activity. The purpose of this study was to evaluate the antimicrobial activity of MPDS against microorganisms that have been reported as contact lens and lens case contaminants and causative agents of microbial keratitis., Methods: MPDS was challenged with high numbers of gram-positive and gram-negative bacteria, yeast, mold, and Acanthamoeba. Several lots of product were challenged with at least three separate inocula of each isolate. After exposure to the disinfecting solution, a sample was removed from the product and plated for survivors by suitable recovery methods. The plates were incubated and the number of survivors was enumerated., Results: The results showed that MPDS was bactericidal, fungicidal and amoebicidal against an extensive variety of environmental contaminants of lens care accessories and ocular pathogens. MPDS was capable of killing a broad spectrum of microorganisms. The log reduction exceeded the primary criteria for disinfecting products and produced a notable reduction of other clinical and environmental isolates as well., Conclusions: Opti-Free Express MPDS contains antimicrobial agents that can kill an extensive spectrum of many different types of microorganisms that may contaminate contact lenses and solutions.

We evaluated the antimicrobial activity of chemical and hydrogen peroxide-neutralizer contact lens disinfection systems. The acute activity, storage, and recontamination potential of the two disinfection methods were compared by challenging the disinfectants with Staphylococcus spp., Pseudomonas aeruginosa, Serratia marcescens, Candida spp., and Aspergillus fumigatus. Chemical disinfectants preserved with polyquaternium-1 and polyhexamethylene biguanide and hydrogen peroxide-neutralizer systems with no additional preservatives were tested. Additionally, lens cases from patients using both systems were evaluated. Lens cases from patients using peroxide-neutralizer systems tended toward heavier contamination (31.8%) than the cases disinfected with a chemical system (20.3%, P = 0.16). The laboratory results showed that the differences in activity of chemical and peroxide-neutralizer systems was not statistically significant at the disinfection times against Staphylococcus epidermidis, S. marcescens, Candida parapsilosis, and A. fumigatus (P = 0.1037 to P = 0.5412). A statistical difference was shown against C. albicans (P = 0.0176) in favor of the peroxide-neutralizer systems. The reverse was true during storage. Although the chemical disinfectants maintained the population of microorganisms, the bacteria and yeast increased to over 10(7) CFU/mL in neutralized peroxide systems. Overall, the results emphasize the importance of contact lens products containing preservatives for lasting protection from microorganisms.