title: Corneal parameters of six- to 12-year-old Chinese children.
abstract: OBJECTIVE
  The aim was to determine the corneal parameters in low to moderate myopic Chinese children and to investigate the differences in these corneal parameters between male and female subjects.
  
  
  METHODS
  Refractive errors and corneal parameters were retrieved from subjects who had participated in studies on myopia and astigmatism in 2008 and 2009. Corneal parameters including simulated K (Sim K) and asphericity (Q) at 9.0 mm chord and horizontal visible iris diameter (HVID) were determined for 217 children (112 males and 105 females aged from six to 12 years) using the Medmont E300 topographer.
  
  
  RESULTS
  The Q of the corneas was -0.44 ± 0.12 along the flat meridian and -0.22 (-0.70 to 0.63) along the steep meridian. The HVID and Sim K of male subjects were larger and flatter than female subjects. The mean HVID of male and female subjects was 11.3 ± 0.3 mm and 11.1 ± 0.30 mm, respectively. The mean Sim K value in male and female subjects was 7.91 ± 0.24 mm and 7.79 ± 0.21 mm, respectively, along the flat meridian, and was 7.65 ± 0.26 mm and 7.53 ± 0.24 mm, respectively, along the steep meridian.
  
  
  CONCLUSIONS
  All corneas were prolate elliptical in shape along the flat meridian and the peripheral flattening rate was found to be greater along the flat meridian. A greater flattening rate was observed in the corneas of Chinese children when compared to that of Caucasian children. The Q between male and female subjects was not significantly different. Male subjects tended to have larger HVID and flatter corneas than female subjects.
authors.affiliation: School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China. so.dede@polyu.edu.hk
authors.forename: Ka Yin
authors.initials: KY
authors.lastname: Chan
authors.forename: Sin Wan
authors.initials: SW
authors.lastname: Cheung
authors.forename: Pauline
authors.initials: P
authors.lastname: Cho
mesh_terms: D044466:Asian People / Q000706:statistics & numerical data*; D001251:Astigmatism / Q000208:ethnology* / Q000473:pathology* / Q000628:therapy; D002648:Child; D003263:Contact Lenses, Hydrophilic / Q000706:statistics & numerical data; D003315:Cornea / Q000473:pathology*; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D009216:Myopia / Q000208:ethnology* / Q000473:pathology* / Q000628:therapy; D015995:Prevalence; D012720:Severity of Illness Index; D017678:Sex Distribution