Efficacy of contact lens storage solutions against different Acanthamoeba strains

Purpose: This study was undertaken in order to determine the susceptibility of acanthamoebae to various contact lens disinfecting systems, with respect to type of disinfectant and exposure time. Methods: Ten contact lens solutions, including one new system, were tested for their effectivities against cysts of three Acanthamoeba strains. Of main interest was ail incubation time of 8 hours (overnight disinfection) and cyst quantities of 103 and 104, respectively. Results: Boston (TM) Advance (polyaminopropyl biguanide 0.0005%, chlorhexidine 0,003%) for the storage of rigid gas permeable contact lenses destroyed the cysts of all strains at either concentration within one hour of exposure. Meni Care Plus (polyhexamethylene biguanide 0.0005%) also destroyed 103 cysts of all strains, however, 104 Cysts only of two strains within one hour; after an exposure time of 8 hours all cysts were killed. The disinfecting solutions for soft contact lenses did not kill 104 cysts of either strain after 8 hours of incubation time. Conclusion: Two of the tested contact lens solutions (the ones for rigid gas permeable lenses) destroyed the cysts of all strains. One of these, containing a combination of two amoebicidal ingredients even after only one hour of exposure time.