title: Distribution of ocular biometry in 7- and 14-year-old Chinese children.
abstract: OBJECTIVE
  To describe distributions of ocular biometry and their associations with refraction in 7- and 14-year-old children in urban areas of Anyang, central China.
  
  
  METHODS
  A total of 2271 grade 1 students aged 7.1 ± 0.4 years and 1786 grade 8 students aged 13.7 ± 0.5 years were measured with ocular biometry and cycloplegic refraction. A parental myopia questionnaire was administered to parents.
  
  
  RESULTS
  Mean axial length, anterior chamber depth, lens thickness, central corneal thickness, corneal diameter, corneal radius of curvature, axial length/corneal radius of curvature ratio, and spherical equivalent refraction were 22.72 ± 0.76 mm, 2.89 ± 0.24 mm, 3.61 ± 0.19 mm, 540.5 ± 31 μm, 12.06 ± 0.44 mm, 7.80 ± 0.25 mm, 2.91 ± 0.08, and +0.95 ± 1.05 diopters (D), respectively, in 7-year-old children. They were 24.39 ± 1.13 mm, 3.42 ± 0.41 mm, 3.18 ± 0.24 mm, 548.9 ± 33 μm, 12.03 ± 0.43 mm, 7.80 ± 0.26 mm, 3.13 ± 0.14, and -2.06 ± 2.20 D, respectively, in 14-year-old children. Compared with 7-year-old children, the older group had significantly more myopia (-3.0 D), longer axial length (1.7 mm), deeper anterior chamber depth (0.3 mm), thinner lens thickness (-0.2 mm), thicker central corneal thickness (10 μm), and greater axial length/corneal radius of curvature ratio (0.22) (all p < 0.001), as well as smaller corneal diameter (-0.03 mm, p = 0.02) and similar corneal radius of curvature. Sex differences were similar in both age groups, with boys having longer axial length (0.5 mm), deeper anterior chamber depth (0.1 mm), shorter lens thickness (0.03 mm), greater central corneal thickness (5 μm), greater corneal diameter (0.15 mm), and greater corneal radius of curvature (0.14 mm) than girls (all p < 0.01). The most important variables related to spherical equivalent refraction were vitreous length, corneal radius of curvature, and lens thickness.
  
  
  CONCLUSIONS
  The 14-year-old group had larger parameter dimensions than the 7-year-old group except for corneal radius of curvature (unchanged) and lens thickness and corneal diameter (both smaller). Boys had large parameter dimensions than girls except for lens thickness (smaller). Axial length, corneal radius of curvature, and lens thickness were the most important determinants of refraction.
authors: *MD, PhD †MD ‡PhD §DSc, FAAO Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China (S-ML, Y-HZ, S-YL, M-TK, ZY, NW); Anyang Eye Hospital, Henan Province, China (HL, L-RL, Y-PW); Zhengzhou Second Hospital, Henan Province, China (X-YY); Department of Epidemiology and Health Statistics, Peking University School of Public Health, Beijing, China (S-YZ); Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, New South Wales, Australia (BG, PM); and School of Optometry and Vision Science and Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, Australia (DAA).
authors: Shi-Ming
authors: SM
authors: Li
authors: Si-Yuan
authors: SY
authors: Li
authors: Meng-Tian
authors: MT
authors: Kang
authors: Yue-Hua
authors: YH
authors: Zhou
authors: He
authors: H
authors: Li
authors: Luo-Ru
authors: LR
authors: Liu
authors: Xiao-Yuan
authors: XY
authors: Yang
authors: Yi-Peng
authors: YP
authors: Wang
authors: Zhou
authors: Z
authors: Yang
authors: Si-Yan
authors: SY
authors: Zhan
authors: Bamini
authors: B
authors: Gopinath
authors: Paul
authors: P
authors: Mitchell
authors: David A
authors: DA
authors: Atchison
authors: Ningli
authors: N
authors: Wang
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D044466:Asian People / Q000208:ethnology*; D058452:Axial Length, Eye / Q000033:anatomy & histology; D001699:Biometry / Q000379:methods*; D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000208:ethnology*; D008297:Male; D009216:Myopia / Q000208:ethnology*; D012029:Refraction, Ocular / Q000502:physiology; D017678:Sex Distribution; D011795:Surveys and Questionnaires; D014505:Urban Population / Q000706:statistics & numerical data*