Disinfection and sonication: Effect on association of Acanthamoeba cysts with an ionic, high-water content hydrogel contact lens

Sets of 16 quarter segments of ionic, high-water content hydrogel contact lenses were incubated with mature cysts of Acanthamoeba castellanii. Lens pieces with associated amoebae were then incubated overnight at 25°C with one of the following: Prymesoak, Sofab, 10.10, ReNu, Optifree or sterile isotonic saline. Other lens pieces were sonicated at a frequency of 110 cycles/sec for 5 min in one of these systems or sonicated and then incubated overnight in the disinfectant. Subsequent culture for amoebal viability indicated that only Prymesoak and 10:10 provided 100% efficacy of action against lens-associated Acanthamoeba cysts, but Prymesoak required overnight incubation for such an effect. Sonication before incubation did not significantly improve the acanthamoebicidal properties of the disinfecting systems.