Criteria for monocular acuity deficit in infancy and early childhood.

Criteria for judging preferential-looking and operant monocular grating acuity test results in pediatric patients are usually based on the distribution of monocular or binocular grating acuities, interocular differences in grating acuities, or test-retest differences obtained from normal populations. In order to compare the sensitivity and specificity of each criterion, normative data were obtained from infants and young children ranging in age from birth to 5 years with common stimuli and staircase procedure. The sensitivity and specificity of each derived criterion were evaluated in two groups of pediatric patients with unilateral eye disorders. Specificity was high for all criteria, ranging from 0.95 to 0.99. However, monocular and binocular grating acuity norms showed low sensitivity to monocular grating acuity deficit, primarily due to high intersubject variability in the normal population. Intersubject variability was lower for interocular grating acuity differences and for test-retest differences, leading to higher sensitivity of these criteria for monocular grating acuity deficit.