Effects of HEV-Filtering in a Soft Contact Lens on Contrast Sensitivity With and Without Veiling Glare

The contrast sensitivity function (CSF) can be used to assess even subtle changes in visual function. These changes are likely amplified in the presence of a stressor such as glare. In this study, we tested mesopic and photopic CSF in the absence/presence of an ecologically valid glare source. CSF was tested within subjects, comparing a high energy visible (HEV)-filtering contact lens against a clear comparator lens of similar material and design.

This was a randomized, controlled, and double-masked study. Forty participants (19-65 years) provided photopic (n=20) or mesopic (n=20) CSF (1.6, 3.2, 8, 16, and 24 cpd) both with and without veiling glare. CSF was measured using a customized optical system. Two separate light channels were combined with a beam splitter that allowed contrast modulation using sine-wave gratings on glass. Glare was interposed between the grating and the subject's eye using an ancillary xenon-based optics channel.

The mean area under the CSF curve derived for both photopic and mesopic CSF (with and without glare) was significantly improved by use of the HEV-absorbing lens compared with the control. With a glare source, the least-squares mean differences (95% confidence interval) were 0.3 (0.24-0.36) and 0.14 (0.10-0.18) under photopic and mesopic conditions, respectively. In the absence of a glare source, the least-squares mean differences (95% confidence interval) were 0.26 (0.21-0.31) and 0.28 (0.20-0.37) for photopic and mesopic conditions, respectively.

The HEV-absorbing lens significantly improved CSF when tested under mesopic and photopic conditions and both with and without veiling glare.