MONOCULAR ACUITY NORMS FOR THE TELLER ACUITY CARDS BETWEEN AGES ONE MONTH AND 4 YEARS

Purpose. To derive norms for monocular grating acuity and interocular acuity differences that are appropriate for clinical applications usin g the acuity card procedure (ACP) and Teller Acuity Cards (TAC). Metho ds. Monocular acuities were measured in 460 children in 12 age groups between 1 month and 4 years. Inclusion criteria were term birth, good general health and normal development, normal eyes, and cycloplegic re fraction within specific limits. Each child was tested by two ACP test ers who were aware of TAC spatial frequency but not grating location d uring testing. Results. Three monocular tests were completed in the fi rst session in 99% of children. Median time to complete the tests of b oth eyes ranged from 3.2 to 8.4 minutes. Monocular acuity norms were c alculated using 95% and 99% prediction limits. The new norms spanned h igher spatial frequencies than the preliminary ACP norms between ages 1 month and 18 months but were similar between 24 and 36 months. The l ower normal 2.5% limits were similar to lower limits of other normativ e studies. The interocular acuity difference was zero or 0.5 octave in 99% of subjects of all ages. Acuities obtained by the same tester on different days and by different testers on the same day were within 0. 5 octave in at least 90% of subjects, comparable to previous studies. Conclusions. This study provides monocular acuity norms that are appro priate for clinical settings in which the ACP and TAC are used and sho uld replace the preliminary ACP norms.