title: [The relationship between refractive error and influencing factors in children].
abstract: OBJECTIVE
  To investigate the influence of refractive factors, including axial length, cornea power and astigmatism, and total astigmatism to refractive errors.
  
  
  METHODS
  Axial length (AL) and cornea power (K) of 295 children (590 eyes) aged 8. 43 years old (4-14 years old) were obtained through IOL-Master, refractive error was measured by retinoscope after cycloplegia. The eyes were divided into 7 groups according to their spherical equivalence (SE). The 7 groups were high myopia, moderate myopia, low myopia, emmetropia, low hyperopia, moderate hyperopia and high hyperopia. AL and cornea parameters of different groups were compared using ANOVA and Pearson's correlation was used to analyze the relationship between SE, AL and cornea astigmatism and total astigmatism respectively.
  
  
  RESULTS
  (1) Of the 7 groups, AL was longest in the high myopia group and shortest in the high hyperopia group. There was a statistically significant difference (P < 0.05) in AL among the 7 groups. (2) High and moderate myopes had the greatest K values and though there was no difference between the 2 groups, they had greater K values compared to other groups (P < 0.05). Moderate hyperopes had the smallest K values which were smaller than any other group except high hyperopia group. (3) SE was negatively correlated with K (r = -0.242, P < 0.001) and positively correlated with cornea astigmatism (r = 0.131, P = 0.001) but had no correlation with total astigmatism. AL was negatively correlated with cornea astigmatism (r = -0.218, P < 0.001) and had no correlation with K and total astigmatism. (4) Multiple linear regression using AL, K and age as independent variable and SE as dependent variable was applied to analyze the relationship of these variables, and the equation was.
  
  
  CONCLUSIONS
  The bigger the cornea K value and the longer the AL were, the more myopia the eye was. The study showed that cornea K value of high hyperopes became steeper, indicating that the corneas of high hyperopes tried to compensate for the hyperopic refractive error due to short AL so that the eye can grow toward emmetropization; but the corneas of other groups had the same trend as the AL, which caused myopia or hyperopia together. However, generally speaking, the cornea became steeper as myopia got more severe and flatter as hyperopia more severe.
authors.affiliation: Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Jun-Xing
authors.initials: JX
authors.lastname: Bai
authors.forename: Li
authors.initials: L
authors.lastname: Bao
authors.forename: Meng
authors.initials: M
authors.lastname: Liao
authors.forename: Xiao-Yue
authors.initials: XY
authors.lastname: Wang
authors.forename: Long-Qian
authors.initials: LQ
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D001251:Astigmatism / Q000150:complications; D058452:Axial Length, Eye / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003315:Cornea / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D012030:Refractive Errors / Q000209:etiology*