Teller Acuity Card norms with and without use of a testing stage

To determine whether norms obtained using the Teller Acuity Card stage are appropriate for comparison with results obtained when the stage is not used.

Eighty children were tested, 20 each at 3.5, 11, 17, and 30 months of age. Binocular grating acuity was measured once with Teller Acuity Cards presented with the stage and once without the stage. Test order was counterbalanced across subjects. Testers were aware that gratings progressed from lower to higher spatial frequencies, but were masked to the absolute spatial frequency of the grating on each card. Testers were masked to acuity results until the child completed testing.

Repeated measures ANOVA with age as a between-subjects variable and test setting as a within-subjects variable showed a significant effect of age (p < 0.001) and test setting (p < 0.001), and a significant interaction between age and test setting (p < 0.01). Post-hoc comparisons (with Bonferroni correction) showed that the difference in acuity results obtained with the stage versus without the stage was significant at 17 months (p < 0.05), but not at 3.5, 11, or 30 months.

Grating acuity norms obtained with the Teller Acuity Card stage are appropriate for comparison with data obtained without the stage in children 3.5, 11, and 30 months of age. However, when 17-month-old children are tested without the stage, comparison of results with norms obtained with the stage is problematic, because testing without the stage results in reduced acuity scores in this age group.