Objective To investigate the visual acuity and refraction of preschoolers and to discuss the referral criteria for vision and refraction screening. Methods It was a cross-sectional study. Preschool children from 24 kindergartens in the Haidian area were selected for vision testing and refraction measurement. Distance visual acuity was tested by the child symbols chart in 3-year-old children and the logarithmic chart in 4- to 6-year-old children. Refractive error was measured with the Welch Allyn SureSight with noncycloplegy. Medians (M)(Q1-Q3) were used to describe visual acuity and refraction. Rank sum tests were used to analyze the differences in vision and refraction for the different ages. Ranges of normal values were calculated by percentiles. Results The M(Q1~Q3) of the sphere was 1.25 D (1.00-1.75 D) in 3- and 4-year-olds, and 1.50 D (1.00-1.75 D) in 5- and 6-year-old children. The difference in spheres for the different ages was statistically significant (χ2=77.60, P<0.01). The M(Q1~Q3) of the cylinder was -0.50 D (-0.75- -0.25 D) for all ages. The difference in cylinders for different ages was statistically significant (χ2=60.41, P<0.01). The Wilcoxon test for two independent samples showed that the difference between 3-year-olds and 4-year-olds was statistically significant (Z=-4.75, P<0.008). The cylinders of the 3-year-olds were smaller than those for other children. The M(Q1~Q3) values for vision were 0.6 (0.6-0.7) in three-year-olds, 0.8 (0.8-1.0) in four-year-olds and 1.0 (1.0-1.0) in five- and six-year-olds. The differences in vision among the different ages were statistically significant (χ2=11 323.87, P<0.01). The Wilcoxon test for two independent samples showed that the difference between any pair of groups was statistically significant (P<0.008). Visual acuity increased with age in preschool children. Among children with normal vision, the P2.5~P97.5 of the spheres was 0.50-2.75 D in three-year-olds, 0.50-2.50 D in four-year-olds, 0.50-2.75 D in five-year-olds and 0.50-3.00 D in six-year-olds. The P5 of the cylinders was -1.50 D in 3-year-olds and -1.25 D in 4- to 6-year-old children. Among children with normal refraction, the P5 of vision was 0.6 in three- and four-year-olds and 0.8 in five- and six-year-olds. Cylinders were more effective in improving vision than spheres. Conclusion The referral criteria for vision are worse than 0.6 for children three and four years old and worse than 0.8 for five and six years old. The referral criteria for the sphere are ≤+0.25 D and ≥+3.00 D for 3- to 6-year-old children. The referral criteria of the cylinder are ≤-1.75 D for children three years old and ≤-1.50 D for four to six years of age. The referral criteria of spheres can be broad, but the referral criteria for astigmatism should be strict.
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