Monocular acuity norms for the Teller Acuity Cards between ages one month and four years.

PURPOSE To derive norms for monocular grating acuity and interocular acuity differences that are appropriate for clinical applications using the acuity card procedure (ACP) and Teller Acuity Cards (TAC). METHODS 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 refraction within specific limits. Each child was tested by two ACP testers who were aware of TAC spatial frequency but not grating location during testing. RESULTS Three monocular tests were completed in the first session in 99% of children. Median time to complete the tests of both eyes ranged from 3.2 to 8.4 minutes. Monocular acuity norms were calculated using 95% and 99% prediction limits. The new norms spanned higher spatial frequencies than the preliminary ACP norms between ages 1 month and 18 months but were similar between 24 and 36 months. The lower normal 2.5% limits were similar to lower limits of other normative 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 appropriate for clinical settings in which the ACP and TAC are used and should replace the preliminary ACP norms.