Purpose:
To investigate the attachment of Acanthamoeba to the new O2OPTIX (Ciba Vision), second–generation, silicone hydrogel lens, and determine if the presence of a bacterial biofilm coating affects attachment. Amoebal attachment was compared to that of the Focus Night & Day (Ciba Vision), first generation silicone hydrogel lens and the Acuvue (Johnson & Johnson) conventional hydrogel lens.
Methods:
Unworn and Pseudomonas aeruginosa biofilm coated O2OPTIX (lotrafilcon B), Focus Night & Day (lotrafilcon A) and Acuvue (etafilcon A) lens quarters were incubated for 90 minutes in a suspension of plate–cultured Acanthamoeba castellanii trophozoites. Trophozoites attached to one surface of each quarter were counted by direct light microscopy. Sixteen replicates of unworn and biofilm coated lenses of each type were examined. Logarithmic transformation of data allowed the use of parametric ANOVA for statistical analysis.
Results:
No significant difference in attachment was detected between the O2OPTIX lens and the Focus Night & Day lens, but both had significantly more amoeba attached than the conventional hydrogel lens (p<0.001). Biofilm coating of the conventional hydrogel produced a significant increase in attachment (p<0.001), however no such increase was seen with the silicone hydrogel lenses.
Conclusions:
The increased affinity exhibited by Acanthamoeba for the two silicone hydrogel lenses suggest that compared to a convention hydrogel lens, these new lenses may provide a greater risk of infection if Acanthamoebal exposure occurs, for instance when showering, swimming or through non–continuous wear and inefficient lens care regimes. However, this increased risk may be countered by the improved corneal oxygenation and metabolism achieved with these new lens materials.
Keywords: contact lens • Acanthamoeba • keratitis