title: The effect of parental history of myopia on children's eye size and growth: results of a longitudinal study.
abstract: OBJECTIVE
  To evaluate the effect of parental myopia on eye size and growth in Chinese children.
  
  
  METHODS
  A school-based, cross-sectional survey was performed in Chinese children 5 to 16 years of age. A longitudinal cohort study was conducted 1 year later. The effects of parental myopia, parental education level, and near work performed by the child on the refractive error and ocular biometry of the child were assessed.
  
  
  RESULTS
  There were 7560 children enrolled in the initial study (response rate: 76.3%). One year later, 4468 children (response rate: 75.9%) in the original cohort (with the exception of those who had completed primary schooling) were evaluated, to determine eye growth. Although children with a stronger parental history of myopia tended to be less hyperopic before the onset of myopia (spherical equivalent refraction [SER] = 0.43 D, 0.67 D, and 0.68 D in children with two, one, and no myopic parents respectively; P = 0.007), the axial lengths did not follow the same pattern (axial length [AL] = 23.11, 23.07, and 23.15 mm; P = 0.429). Eye growth and myopic shift in refraction occurred more rapidly among children with a stronger parental history of myopia (annual AL growth/myopia progression = 0.37 mm/-0.22 D, 0.26 mm/-0.07 D, and 0.20 mm/-0.02 D in children with two, one, and no myopic parents, respectively; P < 0.001).
  
  
  CONCLUSIONS
  Ocular biometric data in Chinese children suggest that parental history of myopia influences the growth rate of the eye, rather than its size before the onset of myopia, as previously reported in Caucasian children. Further longitudinal studies involving children of different ethnicities are warranted.
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Kowloon, Hong Kong. dennislam_pub@cuhk.edu.hk
authors.forename: Dennis S C
authors.initials: DS
authors.lastname: Lam
authors.forename: Dorothy S P
authors.initials: DS
authors.lastname: Fan
authors.forename: Robert F
authors.initials: RF
authors.lastname: Lam
authors.forename: Srinivas K
authors.initials: SK
authors.lastname: Rao
authors.forename: King S
authors.initials: KS
authors.lastname: Chong
authors.forename: Joseph T F
authors.initials: JT
authors.lastname: Lau
authors.forename: Ricky Y K
authors.initials: RY
authors.lastname: Lai
authors.forename: Eva Y Y
authors.initials: EY
authors.lastname: Cheung
mesh_terms: D000293:Adolescent; D001699:Biometry; D002648:Child; D016241:Child of Impaired Parents; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004522:Educational Status; D005123:Eye / Q000473:pathology*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009216:Myopia / Q000235:genetics*; D010290:Parents; D011795:Surveys and Questionnaires