A clinical comparison of visual acuity between the Cardiff acuity test and the Snelled acuity test under known levels of blur

Abstract

The Cardiff Acuity test was compared to the Snellen Acuity test by measurements taken through 1, 2 and 3 diopters of blur. The Cardiff acuities were taken with both minimum resolvable and minimum detectable criterion. Acuity readings were obtained from 59 eyes (59 subjects) at a distance of 1 meter. Poor correlations were found between Snellen acuities and Cardiff acuities at all levels of blur (r\u3c0.50). Minimum detectable with Cardiff gave the highest (best) acuities followed by minimum resolvable with Cardiff and Snellen measuring the lowest (worst) acuities for each level of blur