title: Physical characteristics of ocular structures in Chinese children with emmetropia.
abstract: OBJECTIVE
  To evaluate whether accommodation has effects on eye elongation.
  
  
  METHODS
  Two hundred seventy-three eyes with a refractive error between +1.0 and -0.5 diopters were divided into three groups: pre-school children, grade-school children, and middle-school children. Ocular structures were measured using autorefraction and A-scan ultrasonography.
  
  
  RESULTS
  There was a negative correlation between age and corneal power (r = -0.227, P = .0001), lens thickness (r = -0.263, P = .00001), and Gullstrand lens power (r = -0.452, P << .0001). There was a positive correlation between age and axial length (r = -0.432, P << .0001) and vitreous chamber depth (r = 0.505, P << .0001). Mean corneal power (P < .001) and lens power (P < .001) were significantly greater in pre-school children than in grade-school children, whereas axial length (P < .001) and vitreous chamber depth (P < .001) were greater in grade-school children. Mean lens thickness (P = .01) and lens power (P = .07) were higher in grade-school children than in middle-school children, whereas axial length (P = .024) and vitreous chamber depth (P < .001) were higher in middle-school children.
  
  
  CONCLUSIONS
  Ocular structures may play different roles in maintaining emmetropia. Accommodation during near work and its potential attendant hyperopic defocus could potentially drive eye elongation.
authors.affiliation: Putuo Hospital, Shanghai Chinese Traditional Medicine University, Shanghai, China.
authors.forename: Zhen-Yong
authors.initials: ZY
authors.lastname: Zhang
authors.forename: Ren-Yuan
authors.initials: RY
authors.lastname: Chu
authors.forename: Xing-Ru
authors.initials: XR
authors.lastname: Zhang
authors.forename: Xing-Tao
authors.initials: XT
authors.lastname: Zhou
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hoffman
authors.forename: Jin-Hui
authors.initials: JH
authors.lastname: Dai
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000375:Aging / Q000502:physiology; D000867:Anterior Chamber / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D044466:Asian People; D058452:Axial Length, Eye / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D003315:Cornea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D058453:Emmetropia / Q000502:physiology*; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008297:Male; D014463:Ultrasonography