title: Prevalence of high astigmatism in children aged 3 to 6 years in Guangxi, China.
abstract: OBJECTIVE
  To investigate the prevalence and type of high astigmatism among children aged 3 to 6 years in Guangxi, a relatively undeveloped province in western China, and to examine the correlation between astigmatism and visual acuity.
  
  
  METHODS
  Children aged 3 to 6 years in Nanning, the capital of Guangxi Province, participated in a population-based survey using a cluster random sampling technique. Eye examinations included autorefraction, visual acuity measurements, and assessments of the external eye, anterior segment, media, and fundus. Data for the right eyes were analyzed.
  
  
  RESULTS
  Among the 2304 children examined, the overall prevalence of high astigmatism (≥1.25 diopters by noncycloplegic SureSight autorefraction) was 12.7% (95% confidence interval, 11.3 to 14.0%). The age-specific prevalences of high astigmatism in 3-, 4-, 5-, and 6-year-old children were 13.8, 13.2, 12.9, and 8.1%, respectively. The prevalence of high astigmatism did not vary with age or gender (p > 0.05). The majority of cases of high astigmatism were with-the-rule astigmatism (82.9%), followed by against-the-rule (12.6%) and oblique (4.5%) astigmatism. A linear correlation was found between astigmatism magnitude and visual acuity (logMAR acuity = 0.068 + 0.055 × astigmatism) in all participants. Multiple linear regression analysis further showed that the correlation of astigmatism with visual acuity was magnitude dependent (β = 0.240). When with-the-rule astigmatism was used as a reference group, against-the-rule astigmatism (β = 0.137) and oblique astigmatism (β = 0.154) were closely correlated with visual acuity.
  
  
  CONCLUSIONS
  High astigmatism was moderately prevalent among children aged 3 to 6 years in Guangxi Province. With-the-rule astigmatism was the dominant form of astigmatism. Magnitude- and orientation-dependent correlations of astigmatism with visual acuity were confirmed.
authors.affiliation: *MPH †MSc ‡MBBS Visual Science and Optometry Center of Guangxi, People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China (XX, W-ML, J-ZH, WQ-L, H-TL, QL, W-XZ, E-WL); and Wuhan Aier Ophthalmological Hospital, Wuhan, Hubei, China (Y-JY).
authors.forename: Xin
authors.initials: X
authors.lastname: Xiao
authors.forename: Wei-Min
authors.initials: WM
authors.lastname: Liu
authors.forename: Ying-Jia
authors.initials: YJ
authors.lastname: Ye
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Huang
authors.forename: Wu-Qiang
authors.initials: WQ
authors.lastname: Luo
authors.forename: Hong-Ting
authors.initials: HT
authors.lastname: Liu
authors.forename: Quan
authors.initials: Q
authors.lastname: Lin
authors.forename: Wu-Xiao
authors.initials: WX
authors.lastname: Zhao
authors.forename: En-Wei
authors.initials: EW
authors.lastname: Lin
mesh_terms: D001251:Astigmatism / Q000145:classification / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D014792:Visual Acuity / Q000502:physiology