Development of Visual Acuities in Infants

Abstract

The development of visual acuities in infancy assessed by preferential looking (PL) is discussed with regard to methodological problems and clinical applications. Grating acuity develops up to about 12 cpd in the first year of life. The oblique effect was found at an age younger than 6 months. There was no evidence for meridional amblyopia in the first year of life. Monocular measures of acuity revealed the suppressive interaction between the eyes in strabismic amblyopia and monocular deprivation. The discrepancy between the results obtained by PL and those by VEP technique is also discussed. The development of stereopsis, in contrast to grating acuity, is marked by a sudden onset at an average age of 4 months followed by a rapid increase in stereoacuity. Another hyperacuity, vernier acuity, was also measured recently by PL using a vernier-motion-sound display. It was found to be superior to grating acuity by 4 months of age, about the same as the onset age of stereopsis. Thus, a common cortical basis for the development of hyperacuities was suggested.