Comparative clinical performance of two silicone hydrogel contact lenses for continuous wear

Background: Silicone hydrogel soft contact lenses are now available for use on a 30-day continuous wear basis. The aim of this study was to compare the clinical performance of two such lenses. Methods: In a single-centre, randomised, subject-masked, two-period crossover study, 30 subjects wore a pair of PureVision lenses (Bausch & Lomb) and a pair of Focus Night & Day lenses (CIBA Vision), alternately, for successive eight-week periods. Assessment was made of lens fit and surface characteristics, logMAR visual acuity, ocular response and subjective reaction. Results: Lens fit, deposition and post-lens debris were similar for the two lens types. High contrast visual acuity was statistically significantly better for the PureVision lens, as was the subject-reported quality of vision, although these differences were not considered clinically significant. For both lenses, limbal and conjunctival redness reduced throughout the duration of the study, whereas there was a slight increase in the overall amount of corneal staining. The incidence of mucin balls peaked four weeks after commencing lens wear and began to decline thereafter; more mucin balls were noticed in subjects wearing Focus Night & Day lenses. No differences between the lenses were observed for any other biomicroscopic signs. Conclusions: This study demonstrates similar clinical performance with the two silicone hydrogel lenses evaluated. We believe that, with careful monitoring, both of these newgeneration lenses can be prescribed for continuous wear.