[Use of a rinsing solution for contact lenses in the prevention of amebic keratitis]

Recent reports incriminating Acanthamoeba, a small free-living amoeba, wide-spread in environmental soils and waters, in acanthamoebic keratitis cases wearing soft contact lenses, drew attention to cleaning solutions for contact lenses. The purpose of this report is to discuss the amoebicidal action of a rinsing solution containing 0.001% thimerosal. A. castellanii cysts and trophozoites were incubated with the rinsing solution. Amoeba saline was used as control solution. After 1 h to 96 h of contact time, the survival was studied by growing of trophozoites and excystment of cysts on cultures. The results indicate that trophozoites were destroyed by the rinsing solution after 6 hours, whereas for cysts a negative culture was obtained after 72 h to 96 h. The amoebicidal and cysticidal action of this solution containing mercury corroborates our preceding experience on the effects of mercury derivates on amoebae. The use of amoebicidal solutions in contactology could inhibit and even destroy amoebae on contaminated lenses preventing severe keratitis.