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Choosing appropriate tools and referral criteria for vision screening of children aged 4–5 years in Canada: a quantitative analysis
  1. Mayu Nishimura1,2,
  2. Agnes Wong1,3,4,
  3. Ashley Cohen5,
  4. Kevin Thorpe4,5,
  5. Daphne Maurer2,4
  1. 1 Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada
  2. 2 Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, Ontario, Canada
  3. 3 Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada
  4. 4 Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
  5. 5 Applied Health Research Centre, Li Ka Shing Knowledge Institute, Toronto, Ontario, Canada
  1. Correspondence to Dr Mayu Nishimura; mayu.nishimura{at}


Objectives To assess the diagnostic accuracy of five vision screening tools used in a school setting using sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

Design We compared the results of the five best evidence-based screening tools available in 2014 to the results of a comprehensive eye exam with cycloplegic refraction by a licenced optometrist. Screening included Cambridge Crowded Acuity Cards, Plusoptix S12 and Spot photoscreeners, Preschool Randot Stereoacuity Test and the Pediatric Vision Scanner (PVS). Referral criteria followed AAPOS (2013) guidelines and published norms.

Setting A large school in Toronto, Canada, with 25 split classrooms of junior kindergarten (JK: 4 year olds) and senior kindergarten (SK: 5 year olds) children.

Participants Over 2 years, 1132 eligible children were enrolled at the school. After obtaining parental consent, 832 children were screened. Subsequently, 709 children had complete screening and optometry exam data.

Main outcome measures The presence/absence of a visual problem based on optometrist’s assessment: amblyopia, amblyopia risk factors (reduced stereoacuity, strabismus and clinically significant refractive errors) and any other ocular problem (eg, nystagmus).

Results Overall, 26.5% of the screened children had a visual problem, including 5.9% with amblyopia. Using all five tools, screening sensitivity=84% (95% CI 78 to 89), specificity=49% (95% CI 44 to 53), PPV=37% (95% CI 33 to 42), and NPV=90% (95% CI 86 to 93). The odds of having a correct screening result in SK (mean age=68.2 months) was 1.5 times those in JK (mean age=55.6 months; 95% CI 1.1 to 2.1), with sensitivity improved to 89% (95% CI 80 to 96) and specificity improved to 57% (95% CI 50 to 64) among SK children.

Conclusions A school-based screening programme correctly identified 84% of those kindergarten children who were found to have a visual problem by a cyclopleged optometry exam. Additional analyses revealed how accuracy varies with different combinations of screening tools and referral criteria.

  • health policy
  • protocols & guidelines
  • ophthalmology
  • paediatric ophthalmology
  • strabismus

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  • Contributors MN is the first author, assembled, cleaned and analysed the data, interpreted results and wrote and revised the manuscript. AW and DM are senior authors; they devised the project, supervised data collection, interpreted the results critically and revised the manuscript. AC and KT are the biostatisticians who estimated sample size and carried out the bootstrapping analyses. All authors had full access to the data in the study and can take responsibility for its integrity and accuracy of the analyses. The authors attest that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding This research was supported by a Collaborative Health Research Project grant from Canadian Institutes of Health Research and Natural Sciences and Engineering Research Council of Canada to DM and AW, a Joanne Angle Investigator Award from Prevent Blindness America to AW and private donations.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement The full data set is available on request from the corresponding author at or senior author DM at until 7 years after publication, at which time the data will be destroyed and deleted securely in accordance with data management policies of SickKids Hospital (Toronto, Canada).

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