Purpose: To describe the adhesion properties of Acanthamoeba castellanii trophozoites to silicone hydrogel contact lenses of first generation (lotrafilcon A), second generation (galyfilcon A), and third generation (comfilcon A) and correlate the results with their specific surface characteristics, time of interaction, and suspension media.
Methods: Qualitative and quantitative assessments of the adhesion of 200 trophozoites of A. castellanii on contact lenses in culture medium (Bacto Casitone) and isotonic saline (IS) at different time points (15 minutes and 6 hours) were determined.
Results: By scanning electron microscopy, A. castellanii trophozoites were observed firmly adhered to the surface of hydrogel lenses after 15 minutes of interaction. The surface of lotrafilcon A lenses on which amoebae adhere better (16.4±10.2 amoebae/lens section) is rough and folded, which increases the contact surface with trophozoites, allowing acanthopodia to attach firmly. Contrarily, galyfilcon A lenses have a smoother surface, and lower numbers of amoebae were observed adhered to these lenses (4.7±2.9 amoebae/lens section). Even fewer amoebae adhered to the smoother surface of the comfilcon A lens (2.2±1.7 amoebae/lens section). Trophozoites showed similar behavior in both Bacto Casitone medium and IS.
Conclusion: A rough surface may contribute to better adhesion of amoebae to silicone hydrogel lenses. Although a reduced numbers of trophozoites adhered to smooth lenses, trophozoites are a risk factor for amoebic keratitis. Isotonic saline facilitated trophozoite survival, suggesting that homemade saline solutions may contribute to the persistence of trophozoites, especially when there is no proper hygiene regimen used with the contact lens cases.
School of Superior Studies Iztacala (M.A.O-M., A.B-E., A.R.M-C.), Medicine, Universidad Nacional Autónoma de México, Los Reyes Iztacala, Tlalnepantla, Mexico; Department of Infectomics and Molecular Pathogenesis (A.G-R., L.S-V., A.M-P.), Center for Research and Advanced Studies, Mexico City, Mexico; and School of Superior Studies Iztacala (A.D-D.), Biology, Universidad Nacional Autónoma de México, Los Reyes Iztacala, Tlalnepantla, Mexico.
Address correspondence to Maritza A. Omaña-Molina, Ph.D., FESI, Medicine, UNAM, Av. de los Barrios No. 1, Los Reyes Iztacala, Tlalnepantla C. P. 54090, Mexico; e-mail: email@example.com
Supported by grants provided by Universidad Nacional Autónoma de México (UNAM) Facultad de Estudios Superiores (FES) Iztacala Programa de Apoyo a los Profesores de Carrera (PAPCA) 2010–2011 (project no. 14).
The authors have no other funding or conflicts of interest to disclose.
Accepted January 16, 2014