title: [Comparison between binocular, open-field auto ref/keratometer and conventional autorefractor].
abstract: OBJECTIVE
  To compare the refractive results between open-field auto ref/keratometer and conventional autorefractor, and to investigate the effect of cycloplegic to this difference.
  
  
  METHODS
  Three hundred and four primary and secondary school students were consecutively enrolled in Beijing Tongren Hospital. Non-cycloplegic and cycloplegic objective refractions were performed for each subject by conventional autorefractor (Accuref-K9001, Shin Nippon, Japan) and binocular, open-field auto ref/keratometer (Grand Seiko Co., Ltd., Hiroshima, Japan). The coincidence rate of sphere, spherical equivalent (SE) and axis (defined as difference of diopter ≤ 0.50 D, difference of axis degree ≤ 20°) were calculated; Bland-Altman and distribution analysis were performed according to mean and difference of SE.
  
  
  RESULTS
  The coincidence rate of sphere, SE and axis were 77.3%, 78.6% and 66.0% before cycloplegic and increased to 94.4%, 95.1% and 69.5% after cycloplegic, respectively. The difference (95%CI) of SE before cycloplegic between these two refractometers was 0.12 (-1.04 to 1.29) D and was positively correlated with the mean of SE (after cycloplegic) (r(pearson) = 0.21, P < 0.001). The difference (95%CI) of SE after cycloplegic was -0.08 (-0.60 to 0.45) D. The difference (95%CI) of SE of K9001 autorefractor before and after cycloplegic was larger than that of WAM autorefractor [0.51 (-0.83 - 1.84) D and 0.31 (-0.66 to 1.28) D, P < 0.001]. Before cycloplegic, SE measured by WAM autorefractor showed myopic more than 0.25 D than K9001 (group 1) was found in 51 (16.8%) subjects; difference within 0.25 D was found in 160 (52.6%) subjects; hyperopic more than 0.25 D (group 3) was found in 93 (30.6%) subjects. After cycloplegic, 69 (22.7%) subjects were found in group 1, and subjects increased to 213 (70.1%) and decreased to 22 (7.2%) in group 2 and group 3, respectively.
  
  
  CONCLUSIONS
  The binocular, open-field auto ref/keratometer provides more hyperopic readings than conventional autorefractor. It will be useful in both clinical screening and scientific research because it produces less instrument myopia than that of conventional autorefractor.
authors.affiliation: Beijing Ophthalmol & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, China.
authors.forename: Xiu-hua
authors.initials: XH
authors.lastname: Wan
authors.forename: Zhong
authors.initials: Z
authors.lastname: Lin
authors.forename: Xiao-gu
authors.initials: XG
authors.lastname: Cai
authors.forename: Li-ya
authors.initials: LY
authors.lastname: Qiao
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Yang
authors.forename: Ning-li
authors.initials: NL
authors.lastname: Wang
authors.forename: Yuan-bo
authors.initials: YB
authors.lastname: Liang
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000175:diagnosis; D015351:Vision Screening / Q000295:instrumentation; D014787:Vision Tests / Q000295:instrumentation*; D058609:Visual Field Tests / Q000295:instrumentation*