目的：调查北京市通州区学龄前儿童散光分布特征，讨论其散光分布类型、程度及对学龄前儿童视力的影响。明确睫状肌麻痹验光对散光数值检测有无影响。方法：横断面研究。于2021-12/2022-01采取整群随机抽样法对北京市通州区1 498名学龄前儿童2 996眼，其中男791名，女707名，3-<4岁222名，4-<5岁521名，5-<6岁647名，6-<7岁108名，进行视力、眼前节、电脑验光及睫状肌麻痹验光检查。结果：睫状肌麻痹前散光率为61.88%(927/1498)，睫状肌麻痹后散光率为64.02%(959/1498)(P=0.095)。睫状肌麻痹后轻度散光率为51.87%(777/1498)，中度散光率为9.41%(141/1498)，重度散光率为2.74%(41/1498)； 各年龄组均以顺规散光为主； 复合远视散光最多。散光导致视力低常者中：低度散光占9.38%，中度散光占25.4%，重度散光占52.6%。结论：学龄前儿童散光发病率较高，轻度散光为主； 睫状肌麻痹验光对散光检出率无明显影响，随着散光度数的增加，其对视力的影响越大。

AIM: To explore the characteristics of astigmatism distribution among preschool children from Tongzhou District, Beijing, discuss its categorizations, severity, and the effect on preschoolers' vision, and clarify the influence of cycloplegic refraction on the detection of astigmatism.METHODS:In this cross-sectional study conducted from December 2021 to January 2022, a cluster random sampling method was utilized to assess 1 498 preschool children(2 996 eyes)from Tongzhou District, Beijing. The sample comprised 791 males and 707 females, with 222 children aged 3 to <4 years, 521 children aged 4 to <5 years, 647 children aged 5 to <6 years, and 108 children aged 6 to <7 years. Evaluations included visual acuity, anterior segment, computerized optometry, and cycloplegic refraction.RESULTS:Prior to cycloplegic refraction, the prevalence of astigmatism was found to be 61.88%(927/1498). For post-cycloplegic refraction, this percentage slightly increased to 64.02%(959/1498, P=0.095). Following cycloplegic refraction, the distribution of astigmatism severity was as follows: 51.87%(777/1498)had mild astigmatism, 9.41%(141/1498)had moderate astigmatism, and 2.74%(41/1498)had severe astigmatism. Astigmatism was predominantly with-the-rule across all age groups, with compound hyperopic astigmatism being the most frequent type. In cases of subnormal vision caused by astigmatism: low degree accounted for 9.38%, moderate degree accounted for 25.4%,and high degree accounted for 52.6%.CONCLUSION:The findings reveal a high incidence of astigmatism in preschool children, predominantly in a mild nature. Cycloplegic refraction was observed to have a negligible effect on the rate of astigmatism detection. Moreover, its impact on vision becomes more significant as the degree of astigmatism increases.