Ability of Two Multipurpose Disinfecting Solutions to Kill Microbe’s Adherent to Contact Lenses

Aim:The aim of this project was to determine the ability of two contact lens disinfecting solutions to kill bacteria and fungi attached to lenses.Methods: Pseudomonas aeruginosa PA181, Stenotrophomonas maltophilia 006 and Fusarium solanii ATCC 36031 were allowed to adhere to contact lenses (comfilcon A and somofilcon A) for one hour.The lenses were washed and then placed into contact lens cases of the two disinfecting solutions (cleadew soft containing povidone-iodine, or OPTIFREE RepleniSH containing polyquaternium-1 and myristamindopropyl dimethylamine) and disinfected for the manufacturers recommended time.Lenses are then washed and any viable bacteria removed and grown on agar plates.Both contact lens types that had been worn for a minimum of 6 hours were also disinfected, and any remaining viable microbes were cultured.Results: After adding microbes to the lenses in the laboratory study, no viable microbes grew from the comfilcon A lenses, but 1-6 colony forming units of bacteria could be grown from the somofilcon A lenses after either type of disinfecting solution was used.After wear, bacteria could be cultured from both lens types after disinfection, with slightly more bacteria being cultured from the front vs. the back surface of the comfilcon A lenses (average cfu/lens 15-190 vs. 5-10).Conclusions: There was no difference in the ability of the disinfecting solutions to kill bacteria adherent to lenses.The finding of viable bacteria remaining on lenses after disinfection reinforces the need to rub and rinse lenses after wear to remove some of these adherent bacteria..