Acanthamoeba adherence to soft contact lens and human corneal stroma

In the present study, the adhesibility of Acanthamoeba castellani trophozoites and cysts to hydrogel contact lenses and to human cornea was investigated. Segments of unworn contact lenses were prepared (120 segments in total). In addition, 8 corneal buttons were obtained from 8 enucleated eyes. And each cornea cut into 8 radial segments. To these lens and corneal segments, 1.2 x 106/ml and 1.3 x 106/ml of cysts and trophozoites respectively were added under varying conditions. The adhesion was checked at 0, 3 and 24 hours after the exposure. Adhesion analysis showed that the trophozoites adhered equally well to lens or cornea. There is an increase in the number of trophozoites adhering to contact lenses as well as cornea. This difference is more significant for contact lenses. Washing of contact lenses significantly decreased the adherence of the trophozoites after 3 hours of incubation. When the comparison of adhesion was done between the unwashed worn and unwashed unworn contact lenses, it was observed that there was a significant difference in adherence to new lenses where the adherence was much lower. The study shows that washing of contact lenses does decrease the chances of colonization by Acantamoeba catellani and also that older lenses have higher chances of getting colonized probably due to the occurrence of scratches et. on the surface which may help in colonization.