Abstract
Abstract: :
Purpose: To compare visual acuity results obtained with the original Teller Acuity Cards (Vistech, Inc.), which are no longer commercially available, and a modified, laminated version of the Teller Acuity Cards (Stereo Optical, Inc.), which recently became commercially available. Methods: Subjects were 60 children: 20 at each of 3 ages: 3.5 months, 11 months, and 30 months. Each subject’s binocular grating acuity was measured once with Vistech Teller Acuity Cards and once with Stereo Optical Acuity Cards. Order of testing was counterbalanced across subjects. Testers were aware of the relative spatial frequencies of the gratings, as acuity cards were arranged in ascending order of spatial frequency. Testers were, however, masked to the absolute spatial frequencies of the gratings as the subset of spatial frequencies used for each test was selected according to a psuedo–random order from three possible subsets for each age group. Testers were also masked to acuity results until testing of the child was completed. Results: Repeated measures ANOVA with age as a between–subjects variable and card type as a within–subjects variable showed a significant effect of age (p<0.001) and a significant effect of card type (p<0.001), but no interaction between age and card type. Post–hoc comparisons (with Bonferroni correction) showed that mean acuity score was significantly better with Vistech cards than with Stereo Optical cards at 3.5 months (0.2 octave, p<0.05), 11 months (0.4 octave, p < 0.01), and 30 months (0.7 octave, p < 0.001). Conclusions: These results suggest that normative grating acuity data obtained with the original Vistech Teller Acuity Cards (Salomao & Ventura 1995; Mayer et al 1995) need to be adjusted downward by approximately 0.5 octave to be appropriate for use with the new Stereo Optical Teller Acuity Cards.
Keywords: infant vision • clinical laboratory testing • visual acuity