Clinical evaluation of toric soft lens reproducibility

The manufacturing variability of frequent replacement toric soft lenses is such that some resulting variation in clinical performance can be expected. The purpose of this study was to evaluate the effect of manufacturing variability on the clinical performance of three frequent replacement toric soft contact lenses.

This was a three-part study in which 12 to 14 subjects were enrolled for each part. In each part, subjects were preadapted to the lens type 1 month prior to the assessment visits. Subjects wore a total of 12 test lenses in one eye and, in each case, the clinical performance was compared with a control lens of the same type worn in the other eye that was removed between assessments but not replaced. The study lenses were Acuvue Toric (Vistakon), Focus Toric (Ciba Vision) and FreshLook Toric (Wesley lessen).

Two lens types (Focus Toric and FreshLook Toric) showed significantly greater variability with the test lenses compared with the nonreplaced control lenses with several variables: lens fit, visual acuity, and subjective vision quality. One lens (Focus Toric) also showed greater variability of orientation position, and another (Acuvue Toric) showed greater variability in subjective vision quality.

The study demonstrated variability in aspects of clinical performance, which appear to be linked to variability of manufacturing output. With toric soft lenses used on a frequent replacement basis, better reproducibility is needed if consistent clinical performance is to be maintained.