title: Measurement of refractive error in Native American preschoolers: validity and reproducibility of autorefraction.
abstract: OBJECTIVE
  To examine (1) reproducibility of cycloplegic retinoscopy (C-RNS), cycloplegic autorefraction (C-Autoref), and noncycloplegic autorefraction (NC-Autoref), and (2) validity of C-Autoref and NC-Autoref compared with C-RNS in preschoolers with astigmatism.
  
  
  METHODS
  Subjects were 36 Native American preschoolers. Three measurements of right eye refractive error were obtained with each of three methods: C-RNS (by three different retinoscopists), C-Autoref, and NC-Autoref (Nikon Retinomax K+). Vector methods (vector dioptric distance, VDD) were used in the analyses.
  
  
  RESULTS
  Mean reproducibility was 0.41 D (SD = 0.18) for C-RNS, 0.25 D (SD = 0.17) for C-Autoref, and 0.37 D (SD = 0.21) for NC-Autoref. Mean agreement between C-Autoref and C-RNS ranged from 0.51 to 0.61 VDD (SD = 0.24 to 0.35), and ranged from 1.66 to 1.74 VDD (SD = 1.11 to 1.25) for agreement between NC-Autoref and C-RNS. Mean bias was -0.07 +0.21 x 149 and -1.33 +0.34 x 178 for C-Autoref and NC-Autoref, respectively.
  
  
  CONCLUSIONS
  C-Autoref provided reliable and valid measurements of refractive error in young children. NC-Autoref measurements were reliable within subjects, but there was large variability in validity among subjects.
authors.affiliation: Department of Ophthalmology, The University of Arizona, Tucson 85711, USA. emharvey@u.arizona.edu
authors.forename: E M
authors.initials: EM
authors.lastname: Harvey
authors.forename: J M
authors.initials: JM
authors.lastname: Miller
authors.forename: V
authors.initials: V
authors.lastname: Dobson
authors.forename: R
authors.initials: R
authors.lastname: Tyszko
authors.forename: A L
authors.initials: AL
authors.lastname: Davis
mesh_terms: D001130:Arizona; D001251:Astigmatism / Q000175:diagnosis* / Q000208:ethnology*; D002675:Child, Preschool; D003519:Cyclopentolate / Q000008:administration & dosage; D006801:Humans; D007198:Indians, North American; D011680:Pupil / Q000187:drug effects; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D014787:Vision Tests / Q000295:instrumentation*
chemical_list: D003519:Cyclopentolate