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 (x2=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 (x2=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 (x2=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.%目的 了解学龄前儿童的视力和屈光发育状况,探讨该年龄段儿童弱视筛查中的视力和屈光度筛选标准.方法 横断面调查研究.对海淀区24所幼儿园3～6岁儿童进行视力和屈光度检查.3岁儿童采用图形视力表,4岁以上用标准对数视力表.屈光度检查用SureSight手持式自动验光仪在自然状态下进行.用M(Q1～Q3)描述各年龄组视力和屈光度的分布特征,用秩和检验比较不同年龄组间视力和屈光度分布差异,以百分位数法确定95％参考值范围.结果 球镜度M(Q1～Q3):3岁和4岁均为1.25 D(1.00～1.75 D),5岁和6岁均为1.50 D(1.00～1.75 D),3～6岁不同年龄组间球镜度分布差异有统计学意义(x2=77.60,P＜0.01).柱镜度:各年龄组均为-0.50 D(-0.75～-0.25 D),不同年龄组间柱镜度分布差异有统计学意义(x2=60.41,P＜0.01),两两比较3岁和4岁组之间差异有统计学意义(Z=-4.75,P＜0.008),3岁儿童柱镜度较其他组偏小.视力J:3岁为0.6(0.6～0.7),4岁为0.8(0.8～1.0),5岁和6岁均为1.0(1.0～1.0),不同年龄组间视力分布差异有统计学意义(x2=11 323.87,P＜0.01),两两比较各年龄组间差异均有统计学意义(P＜0.008),随年龄增长视力逐渐提高.视力正常儿童的球镜度P2.5～P97.5:3岁+0.50～+2.75 D,4岁+0.50～+2.50 D,5岁+0.50～+2.75 D,6岁+0.50～+3.00 D,柱镜度P5:3岁-1.50 D,4～6岁-1.25 D;屈光度正常儿童的视力P5分别为3岁和4岁0.6,5岁和6岁0.8.柱镜度数变化对视力的影响较大,球镜度数变化对视力的影响相对较小.结论 视力筛选标准:3岁和4岁＜0.6,5岁和6岁＜0.8:球镜度筛选标准:3～6岁球镜≤+0.25 D和≥+3.00 D;柱镜度筛选标准:3岁≤-1.75 D,4～6岁≤-1.50 D.自然状态下屈光筛查球镜度范围可适当放宽,柱镜度范围应相对严格.
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