Adhesion of Acanthamoeba on Silicone Hydrogel Contact Lenses

To evaluate adhesion of Acanthamoeba trophozoites to different silicone hydrogel contact lens (SHCL) generations with and without multipurpose contact lens care solution (MPS) treatment.

Acanthamoeba lugdunensis L3a trophozoites were inoculated onto discs trimmed from SHCLs: first generation, Air Optix (Lotrafilcon B) with a plasma surface treatment, second generation, Acuvue Oasys (Senofilcon A), which contains an internal wetting agent (Hydraclear), and third generation, Biofinity (Comfilcon A) with no surface treatment. After 18-hour inoculation, the number of adherent trophozoites on SHCLs was counted as the control under phase contrast microscopy. The effects of the 3 different MPSs, Opti-Free Express, ReNu Fresh, and Biotrue, soaking SHCLs for 6 hours, on Acanthamoeba adhesion were analyzed. Scanning electron microscopic examination was performed for assessment of Acanthamoeba attached on the lens surface.

Acanthamoeba trophozoites showed greater adhesion to Air Optix than to Acuvue Oasys and Biofinity (P < 0.05). On Air Optix and Acuvue Oasys, the number of adherent Acanthamoeba was significantly reduced compared with the control after treatment with Opti-Free Express (P < 0.05), but not significantly reduced by treatment with ReNu Fresh and Biotrue (P > 0.05). Acanthamoeba did not adhere to Biofinity regardless of MPSs treatment. Attachment of the acanthopodia of Acanthamoeba on the curved ridge of the Air Optix lens surface was observed.

Acanthamoeba showed greater affinity for the first-generation SHCL and seemed to be more attached on SHCLs with more ridges. MPS with myristamidopropyl dimethylamine reduced the adhesion rate.