Letters: May 30

We read with interest the recent article by Giles and Fahmy (Performance of daily disposables contact lenses with moisturing agents, Optician, May 2) reporting the results of a two-part crossover clinical study sponsored by CIBA Vision involving a comparison of two daily disposable soft contact lenses: CIBA Focus Dailies with AquaComfort Plus with 1-Day Acuvue Moist. We are concerned that the study design incorporates some significant flaws, which should limit the conclusions drawn from the results.

A high proportion of the subjects (65 per cent) enrolled in the study were existing adapted wearers of the same material and brand as one of the test lenses (Focus Dailies). The article does not describe any masking of the test lenses, which raises the significant concern that most subjects would have been pre-biased to one of the study products for the following reasons: