title: Accuracy of noncycloplegic autorefraction in school-age children in China.
abstract: OBJECTIVE
  To evaluate the accuracy of noncycloplegic autorefraction in a representative sample of school-age children in China.
  
  
  METHODS
  Refractive error was measured with an autorefractor, both before and after cycloplegia induced with cyclopentolate, in a population-based sample of 4973 children between the ages of 7 and 18 years. Spherical equivalent refractive error and astigmatism as represented by Jackson crossed-cylinders (J0 and J45) were the main outcome measures.
  
  
  RESULTS
  Noncycloplegic measurements of equivalent spheres were consistently more negative or less positive than those after cycloplegia, with mean +/- SD differences of -1.23 +/- 0.97 D. The differences were particularly large for hyperopic eyes (mean difference of -2.98 +/- 1.65 D for hyperopia of at least +2.00 D) while becoming progressively smaller for emmetropic eyes, and smaller yet for myopic eyes (mean difference of -0.41 +/- 0.46 D for myopia of -2.00 D or more). Increasing age was associated with increased, but clinically insignificant, differences. Little difference was found between noncycloplegic and cycloplegic measurements of astigmatism: mean J0 and J45 differences were -0.08 +/- 0.13 D and -0.01 +/- 0.09 D, respectively.
  
  
  CONCLUSIONS
  Noncycloplegic autorefraction was found to be highly inaccurate in school-age children and, thus, not suitable for studies of refractive error or for prescription of glasses in this population.
authors.affiliation: Department of Ophthalmology, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Jialiang
authors.initials: J
authors.lastname: Zhao
authors.forename: Jin
authors.initials: J
authors.lastname: Mao
authors.forename: Rong
authors.initials: R
authors.lastname: Luo
authors.forename: Fengrong
authors.initials: F
authors.lastname: Li
authors.forename: Gopal P
authors.initials: GP
authors.lastname: Pokharel
authors.forename: Leon B
authors.initials: LB
authors.lastname: Ellwein
mesh_terms: D000293:Adolescent; D002648:Child; D002681:China; D003519:Cyclopentolate / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D009184:Mydriatics / Q000008:administration & dosage; D011680:Pupil / Q000187:drug effects; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis*; D015203:Reproducibility of Results; D014787:Vision Tests / Q000592:standards*
chemical_list: D009184:Mydriatics; D003519:Cyclopentolate