INTEROBSERVER AGREEMENT FOR MEASUREMENT OF GRATING ACUITY AND INTEROCULAR ACUITY DIFFERENCES WITH THE TELLER ACUITY CARD PROCEDURE

Interobserver reliability of the Teller acuity card (TAC) procedure fo r estimating acuity and interocular acuity differences (IADs) was asse ssed with 342 infants and children who had been treated in a neonatal intensive care unit for preterm birth and/or perinatal complications. Subjects were tested binocularly at term and monocularly at 4, 8, 11, 17, 24, 30, 36, and 48 months corrected age with TACs. Testers were ma sked to the location and spatial frequency of the grating on each card . Of the interobserver test-retest scores, 67% differed by no more tha n 0.5 octave, and 87% of the test pairs differed by no more than 1 oct ave. Of the test-retest comparisons of a subject's IAD, 54% showed agr eement of 0.5 octave or better, and 76% differed by no more than 1 oct ave. Interobserver agreement for binocular and monocular tests was sim ilar to that reported previously for visually and neurologically at-ri sk infants and children tested with the forced-choice preferential-loo king procedure or with prototype acuity cards. Interobserver agreement for IAD estimates was somewhat less than that reported for a sample o f infants with ocular disorders. There were no systematic differences in interobserver agreement between eyes tested first and eyes tested s econd, nor was interobserver agreement related to subject's medical di agnosis. Interobserver agreement was influenced, however, by the spati al frequencies of the particular gratings used during testing and, to a limited extent, by the age of the child. The duration of individual tests and observers' ratings of confidence in their acuity estimate we re not reliable indicators of test-retest pairs that were not in agree ment. The results demonstrate the reliability of the TAC procedure, bu t suggest that acuity estimates critical to a patient's diagnosis or t reatment should be confirmed by repeat testing.