Clinical performance of a disability glare tester.

A glare tester was described previously and was found, in the presence of cataracts, to be almost twice as predictive as was Snellen measurement for determining visual acuity outdoors. The current study tests the reproducibility of glare test scores and the influence of refractive error and contrast sensitivity on such scores when used in a clinical environment. Although the effects of visual acuity and impaired contrast sensitivity were found to be statistically significant components of glare test scores, the magnitudes of their effects were found to be clinically insignificant. Sequential retesting of physiologically stable eyes or, in the case of progressive cataracts, within intervals short enough to preclude discernible lenticular changes indicated that, for the most part, reproducibility of glare testing was comparable to that of visual acuity testing.