title: Astigmatism in preschool children in Taiwan.
abstract: OBJECTIVE
  To elucidate the prevalence of astigmatism and its corneal component, the association between the amount of astigmatism and its axis, and the association between the axis of astigmatism and body mass index (BMI) in Taiwanese preschool children.
  
  
  METHODS
  In this population-based study we analyzed 2 data sets, one obtained by retrospective review of vision-screening data and another obtained in a prospective observational study. Each study collected data for age, sex, and refraction status. Autokeratometry, height, and weight measurements were obtained only in the observational study. Astigmatism was classified as with-the-rule, against-the-rule, or oblique.
  
  
  RESULTS
  The prevalence of astigmatism was unassociated with age or sex in both data sets. The retrospective study (1,094 subjects; mean age, 5 years; range, 2.19-7.32 years) revealed that 13.3% of the subjects had astigmatism > or = 1.00 D, and most of them had with-the-rule astigmatism; 4.0% had high astigmatism (>1.50 D). Children with with-the-rule astigmatism had greater mean cylinder power than those with against-the-rule or oblique astigmatism. In the prospective study (190 subjects; mean age, 5.65 years; range, 3.79-6.68 years) astigmatism correlated with its corneal component. Preschoolers with with-the-rule astigmatism and with-the-rule corneal astigmatism had greater BMI and heavier weight than those with against-the-rule or oblique type.
  
  
  CONCLUSIONS
  Astigmatism is common in Taiwanese preschool children. The predominant types are with-the-rule and oblique astigmatism. Most patients with high astigmatism and high corneal astigmatism have with-the-rule type. High BMI or weight is associated with with-the-rule astigmatism and with with-the-rule corneal astigmatism.
authors.affiliation: Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yu-Hung
authors.initials: YH
authors.lastname: Lai
authors.forename: Hsin-Tien
authors.initials: HT
authors.lastname: Hsu
authors.forename: Hwei-Zu
authors.initials: HZ
authors.lastname: Wang
authors.forename: Cheng-Hsien
authors.initials: CH
authors.lastname: Chang
authors.forename: Shun-Jen
authors.initials: SJ
authors.lastname: Chang
mesh_terms: D001251:Astigmatism / Q000453:epidemiology*; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D013624:Taiwan / Q000453:epidemiology; D015351:Vision Screening