Monocular acuity in normal infants: the acuity card procedure.

An "acuity card" technique has been developed for rapid assessment of visual acuity in infants. In this procedure an adult observer shows the infant a series of cards that contain gratings of various spatial frequencies and estimates acuity as the highest spatial frequency that the infant is judged to see. The present paper shows that the acuity card procedure can be used in a laboratory setting to estimate both monocular and binocular acuity in infants 1 to 12 months of age. Four monocular and two binocular acuity estimates were obtained on 36 normal infants, six each at ages 4, 8, and 16 weeks and 6, 9, and 12 months. Acuity estimate means and SD's agreed well with previously established preferential looking (PL) norms for each of the test ages. Time required for a monocular or a binocular test averaged 3 to 6 min.