Evaluation of visual function in preschool-age children using a vision screening protocol

Purpose To evaluate the relationship between uncorrected visual acuity and refraction and binocular function using a vision screening protocol. Methods In total, 760 children (3-6 years old) who were enrolled in 4 nursery schools in Otawara, Japan, were recruited; a total of 1,520 eyes were examined. We assessed uncorrected near visual acuity, manifest refraction, stereopsis, and eye position. Subjects were divided into 4 subgroups according to the lowest uncorrected near visual acuity value compared between the 2 eyes: group 1 (visual acuity [VA] ≤0.00 [logarithm of the minimum angle of resolution]), group 2 (VA 0.15-0.05), group 3 (VA 0.52-0.22), and group 4 (VA >0.52). These parameters were compared among the groups. Results The sample number of each of the 4 sub-groups was as follows: group 1, 608; group 2, 114; group 3, 27; and group 4, 11. The median spherical equivalent values were -1.13 diopter (D) in group 1 and -1.00 in group 2, which were more myopic than group 4. Median cylindrical power in group 1 was 0.25 D, and was the lowest among all groups. In group 1, median anisometropia was 0.38 D and median corneal astigmatism value was 1.13 D; both values were lowest in group 1. With regard to binocular function, 89.6% of the subjects in group 1 had 60 arcseconds or better in near stereopsis and 98.8% had no detectable strabismus, which were significantly different from the findings in the other groups. The percentage of subjects in group 1 who had 80 arcseconds or worse in near stereopsis was 10.4%. In contrast, 90.9% of the subjects in group 4 had 80 arcseconds or worse in near stereopsis, and 18.2% had intermittent or manifest strabismus. Conclusion We suggest that examination of refraction and stereopsis in preschool-age children undergoing vision screening is an important supplement to visual acuity testing.