Monocular acuity in preschool children: Assessment with the Teller and Keeler acuity cards in comparison to the C-test.

The development of monocular grating acuity was studied in 210 children between 1 and 6 years using Teller Acuity Cards (TAC). 95 of these children were also tested with the Keeler Acuity Cards (KAC). Monocular visual acuity measured with the TAC showed a gradual increase from 8.4 to 32.4 c/deg for 7 to 79 month-olds and with the KAC from 14.5 to 31.4 c/deg for 19 to 78 month-olds. Mean visual acuity at 6 years was still 0.5-1.0 octave lower than grating acuity in adults. The results of 95 children tested with TAC and KAC did not indicate any significant differences between the acuity scores obtained with the two tests. Stimulus configuration of the TAC did not result in overestimation of acuity in children 1-6 years of age. In 141 older children (39-79 months), the TAC test was compared with a recognition test (C-test). Children between 3 and 5 years of age reached significantly lower acuities with the C-test than with the TAC. The C-test showed a higher sensitivity for unconnected refractive errors than the acuity card tests.