Visual Profile of Children Passing/Failing a UK School Vision Screening Protocol

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Background: We applied the National Screening Committee vision screening protocol [pass criterion monocular acuity≤0.2LogMAR in both eyes(BE)] to 4-5 year-old children to investigate the visual profile of children who passed/failed. Previous studies have only evaluated those failing. The aim was to derive false positive and negative values, specificity/ sensitivity of the vision screening protocol for detecting significant visual defects (strabismus and significant refractive error) and the utility of a ‘plus blur test’ in identifying hyperopia.
Methods: 294 children (5.2±0.4yrs) participated. In addition to the vision screening protocol (monocular acuity-3m crowded Keeler LogMAR letters), acuities were recorded through +2.50D and +4.00D lenses and ocular alignment and cycloplegic refractive error were assessed. Using acuity measures, participants were classed as passing/failing the screening protocol. Each participant was also classed as having a strabismus and/or significant refractive error (hyperopia≥+4.00DS; myopia≤-0.50DS; astigmatism≤-1.50DC; anisometropia ≥+1.50DS) or no significant visual defects. 
Results: 284 children completed all tests; 27.8% failed to achieve 0.2LogMAR in BE. The acuity pass/fail criterion had a sensitivity of 70.4% and specificity of 82.2% for detecting strabismus and/or significant refractive error. 51.9% (n=41/79) of those who failed had no strabismus or significant refractive error (‘false positives’). Children who passed generally had no visual defects, however 7.8% (n=16/205) did (‘false negatives’).The ‘plus blur tests’ improved sensitivity in detecting significant refractive error (+2.50D & +4.00D 90.7%) but significantly reduced specificity (+2.50D=65.2%;+4.00D=60.9%).
Conclusions: School-entry vision screening is reasonably sensitive and specific for detecting strabismus and significant refractive error. Most children with visions poorer than 0.2 LogMAR need refractive intervention and the majority of the remainder are likely ‘false positives’ for significant visual defects. One in 13 children who pass have either strabismus and/or significant refractive error (7.8%). The inclusion of a ‘plus blur test’ was not a useful addition to the vision screening protocol. 
Key words: vision screening, strabismus, refractive error, amblyopia, sensitivity, specificity
Original languageEnglish
Pages (from-to)36-46
Number of pages11
JournalBritish and Irish Orthoptic Journal
Issue number1
Publication statusPublished (in print/issue) - 26 Mar 2019


  • vision screening
  • strabismus
  • refractive error
  • amblyopia
  • sensitivity
  • specificity


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