Refractive error and preferential looking visual acuity in infants 12-24 months of age: year 2 of a longitudinal study.

This paper presents data from year 2 of a study assessing changes in visual acuity and refractive error in normal, healthy infants between birth and 24 months of age. Visual acuity and refractive error measurements were taken at 2-month intervals on 18 infants, 12-24 months of age. The acuity card preferential looking procedure and Mohindra's near retinoscopy were used for acuity and refractive error measurement. Response to the Stereo Fly was also observed. Mean acuity improved from 6.4 cycles per degree (cpd) (20/93) at 12 months to 20.5 cpd (20/29) at 24 months (SD = 0.5 octave). Refractive error remained in low hyperopia (X = 0.4D, SD = 0.5D). Amount and frequency of astigmatism showed little change. Response to the Stereo Fly improved from 0% at 12 months to 87% at 24 months. The acuity card procedure was easily accomplished, but more difficult with these children at 12-24 months of age than when previously tested between 0-12 months of age.