title: Screening for amblyopia risk factors in pre-verbal children using the Plusoptix photoscreener: a cross-sectional population-based study.
abstract: OBJECTIVE
  To evaluate the accuracy and applicability of Plusoptix photoscreener in screening pre-verbal children at risk of amblyopia.
  
  
  METHODS
  In this cross-sectional population-based study 996 children aged 6-36 months were screened with the Plusoptix. The children underwent complete examinations that included a manual cycloplegic retinoscopy, slit lamp examination, cover test, the Hirschberg test and an assessment of fixation pattern. In addition, the prevalence of amblyogenic risk factors was estimated, the Plusopix measurements were compared with cycloplegic retinoscopy, and the referral criteria were modified to improve the accuracy of the device.
  
  
  RESULTS
  Amblyogenic hyperopia >+3.50 D, myopia >-3.00 D, astigmatism >1.50 D in the orthogonal meridian or >1.00 D in the oblique meridian, or anisometropia >1.50 D was detected in 4.7%, 0.0%, 12.3% and 0.5% of the samples, respectively. The average difference between retinoscopy and photorefraction for spherical equivalence was -0.16 ± 1.0 D (p<0.05). Testability was 98.1% for the Plusoptix. The Plusoptix vision screener referred 47.8% of these children for sensitivity, specificity, positive predictive value and false-negative rates of 100%, 38.7%, 19% and 100%, respectively. These same measurements with the modified referral criteria (hyperopia ≥ 2.00 D in children under 12 months and astigmatism ≥ 1.25 D) were 93.6%, 51.2%, 21.7% and 98.2%.
  
  
  CONCLUSIONS
  The Plusoptix is a useful objective screening instrument, but still has low specificity for detecting amblyopia risk factors in the paediatric population.
authors.affiliation: Eye Research Center of the Mashhad University of Medical Sciences, Khatam-al-Anbia Eye Hospital, Mashhad, Iran.
authors.forename: Ali Akbar Saber
authors.initials: AA
authors.lastname: Moghaddam
authors.forename: Abbas
authors.initials: A
authors.lastname: Kargozar
authors.forename: Mehran
authors.initials: M
authors.lastname: Zarei-Ghanavati
authors.forename: Marzieh
authors.initials: M
authors.lastname: Najjaran
authors.forename: Vahideh
authors.initials: V
authors.lastname: Nozari
authors.forename: Mohammad Taghi
authors.initials: MT
authors.lastname: Shakeri
mesh_terms: D000367:Age Factors; D000550:Amblyopia / Q000175:diagnosis* / Q000453:epidemiology*; D001251:Astigmatism / Q000175:diagnosis / Q000453:epidemiology; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004948:Esotropia / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000175:diagnosis / Q000453:epidemiology; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015351:Vision Screening / Q000295:instrumentation* / Q000379:methods / Q000592:standards*