An analysis of visual performance with soft contact lens and spectacle correction.

This study compares, under controlled conditions and by rigorous statistical analysis, the contrast sensitivity function (CSF) measured with soft-lens and spectacle correction, attempting to resolve the conflicting reports in the literature. Ten non-astigmatic ametropic subjects had the CSF measured at eight spatial frequencies with the two types of visual correction. Analysis of variance revealed statistically significant effects for subjects, stimuli and type of visual correction, statistically superior performance being obtained with soft lenses. However, the actual difference in the CSF for the two forms of correction was small (0.14 log units) and not clinically significant. Comparison of the average CSF for the three highest and lowest spatial frequencies tested revealed a significant advantage in using higher spatial frequencies in the determination of statistical differences in the CSF obtained with different types of visual correction.