Abstract
Abstract: :
Purpose: To establish if the surface treatment procedure, used to overcome the hydrophobic nature of the silicone hydrogel (S-H) material, is responsible for the high level of acanthamoebal attachment to this polymer. Methods: S-H lenses (PureVision, Bausch & Lomb) could not be obtained prior to the plasma oxidation surface treatment. Therefore the silicone elastomer (S-E) lens, Silsoft (Bausch & Lomb) was used as a substitute, as it is silicone based and intrinsically hydrophobic, and therefore has to be subjected to a similar surface treatment procedure. Attachment to treated and untreated S-E lenses was compared with that of treated S-H and a conventional hydrogel control lens (Acuvue, Vistakon). Treated and untreated S-E, S-H and hydrogel lens quarters were incubated for 90 minutes in a suspension of Acanthamoeba castellanii trophozoites. After incubation and rinsing, the trophozoites attached to one surface of each quarter were counted by direct light microscopy. Sixteen replicates were carried out for each lens type. Logarithmic transformation of the data allowed the use of parametric ANOVA. Results: No significant difference in attachment was detected between the treated and untreated S-E lenses, nor were either significantly different from the S-H lenses. However, attachment to all three was significantly different from that of the conventional hydrogel control lens (p<0.001), which had far fewer organisms attached. Conclusion: Surface treatment did not have a significant effect on acanthamoebal attachment to S-E lenses. By inference, from the S-E lens data, it appears that the increased level of attachment seen with the S-H lenses (compared with the conventional hydrogel) is due to an inherent property of the silicone based polymer rather than a side effect of the surface treatment procedure.
Keywords: 367 contact lens • 302 Acanthamoeba • 449 keratitis