8th March 2019, Volume 132 Number 1491

William Muller, Logan Mitchell, Graham Wilson

Amblyopia, or ‘lazy eye’, is the most common ophthalmological condition affecting children, with a prevalence of approximately 1–5%.1–3 It arises from abnormal visual development during childhood, a process occurring competitively…

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This study reviewed the results of the four-year-old vision screening programme (B4 School Check) in Southern and Tairawhiti DHBs over a six-month period in 2016. Of the 2,109 children screened, 176 (8.3%) ‘failed’ the vision test and were referred on to either optometrist or DHB ophthalmology clinic. Only 91 (51.7%) were determined to have been seen as a result of that referral, and of them 39 (42.8%) were found to have normal vision. Of those referred and seen with abnormal vision, the vast majority (>92%) needed glasses for simple refractive error, while only 10% required any treatment other than glasses. Concerningly, 48.3% of children referred from the B4SC vision screening pro-gramme were not able to be confirmed as having received optometric or ophthalmic review as a con-sequence of that referral.



To assess the accuracy of the B4 School Check (B4SC) vision screening programme in two distinct regions of New Zealand.


A retrospective audit of all children who were screened for vision in the Southern and Tairawhiti District Health Boards, between 1 April and 30 September 2016. Results from the B4SC screening programme (n=2,109) were compared to records for all children who were screened and subsequently presented to an optometrist at a DHB eye clinic (n=116).


The B4SC produced a sensitivity in the range of 54.7% to 94.7% and a specificity of 93.8% to 95.7%. There was a low positive predictive value (PPV), between 29.5% and 51.1%, with a relatively high number of false positive referrals. The negative predictive value (NPV) was higher, however, between 97.8% and 99.7%, meaning nearly all children who passed screening had no visual impairment.


The high NPV is reassuring that very few children with visual impairment are missed by screening. The low PPV was consistent with the international literature and is related to a tendency for over-referral from the B4CS programme. Further work could evaluate increasing the threshold for referral to reduce the number of false positive cases.

Author Information

William Muller, Department of Medicine, University of Otago, Dunedin School of Medicine, Dunedin; Logan Mitchell, Consultant Ophthalmologist, Dunedin Hospital, Clinical Senior Lecturer, University of Otago, Dunedin School of Medicine, Dunedin; Graham Wilson, Ophthalmologist, Gisborne Hospital, Clinical Senior Lecturer, University of Otago, Gisborne.


The authors would like to thank The Maurice and Phyllis Paykel Trust for providing scholarship to William Muller to help fund this study. The authors would also like to thank Pat Tuohy and the Ministry of Health for providing help with the study design and data collection. Prof Nick Wilson provided helpful comments in the manuscript. 


Dr Logan Mitchell, Consultant Ophthalmologist, Dunedin Hospital, Clinical Senior Lecturer, University of Otago, Dunedin School of Medicine, Dunedin.

Correspondence Email


Competing Interests



  1. Attebo K, Mitchell P, Cumming R, et al. Prevalence and causes of amblyopia in an adult population. Ophthalmology. 1998 Jan; 105(1):154–9. 
  2. Holmes JM, Clarke MP. Amblyopia. Lancet Lond Engl. 2006 Apr 22; 367(9519):1343–51. 
  3. Robaei D, Rose KA, Ojaimi E, et al. Causes and associations of amblyopia in a population-based sample of 6-year-old Australian children. Arch Ophthalmol Chic Ill 1960. 2006 Jun; 124(6):878–84. 
  4. Chua B, Mitchell P. Consequences of amblyopia on education, occupation, and long term vision loss. Br J Ophthalmol. 2004 Sep; 88(9):1119–21. 
  5. Engel-Yeger B. Evaluation of gross motor abilities and self perception in children with amblyopia. Disabil Rehabil. 2008; 30(4):243–8. 
  6. Daw NW. Critical periods and amblyopia. Arch Ophthalmol Chic Ill 1960. 1998 Apr; 116(4):502–5. 
  7. Epelbaum M, Milleret C, Buisseret P, Dufier JL. The sensitive period for strabismic amblyopia in humans. Ophthalmology. 1993 Mar; 100(3):323–7. 
  8. Hendler K, Mehravaran S, Lu X, et al. Refractive Errors and Amblyopia in the UCLA Preschool Vision Program; First Year Results. Am J Ophthalmol. 2016 Dec; 172:80–6. 
  9. Matsuo T, Matsuo C, Matsuoka H, Kio K. Detection of strabismus and amblyopia in 1.5- and 3-year-old children by a preschool vision-screening program in Japan. Acta Med Okayama. 2007 Feb; 61(1):9–16. 
  10. Kvarnström G, Jakobsson P, Lennerstrand G. Visual screening of Swedish children: an ophthalmological evaluation. Acta Ophthalmol Scand. 2001 Jun; 79(3):240–4. 
  11. Sheridan MD, Gardiner PA. Sheridan-Gardiner test for visual acuity. Br Med J. 1970 Apr; 2(5701):108-9.
  12. Ministry of Health. The B4 School Check: A handbook for practitioners. Wellington: Ministry of Health; 2008. 
  13. New Zealand Health System. 2016. http://www.health.govt.nz/new-zealand-health-system/my-dhb
  14. Langeslag-Smith MA, Vandal AC, Briane V, et al. Preschool children’s vision screening in New Zealand: a retrospective evaluation of referral accuracy. BMJ Open. 2015 Nov 27; 5(11):e009207. 
  15. Juttmann R, Rotterdam AMblyopia Screening Effectiveness Study (RAMSES) steering committee. The Rotterdam AMblyopia Screening Effectiveness Study (RAMSES): compliance and predictive value in the first 2 years. Br J Ophthalmol. 2001 Nov; 85(11):1332–5. 
  16. Peterseim MMW, Papa CE, Wilson ME, et al. The effectiveness of the Spot Vision Screener in detecting amblyopia risk factors. J AAPOS Off Publ Am Assoc Pediatr Ophthalmol Strabismus. 2014 Dec; 18(6):539–42. 
  17. Chang C-H, Tsai R-K, Sheu M-M. Screening amblyopia of preschool children with uncorrected vision and stereopsis tests in Eastern Taiwan. Eye Lond Engl. 2007 Dec; 21(12):1482–8. 
  18. Vision in Preschoolers Study Group. Preschool vision screening tests administered by nurse screeners compared with lay screeners in the vision in preschoolers study. Invest Ophthalmol Vis Sci. 2005 Aug; 46(8):2639–48. 
  19. Tarczy-Hornoch K, Cotter SA, Borchert M, et al. Prevalence and causes of visual impairment in Asian and non-Hispanic white preschool children: Multi-ethnic Pediatric Eye Disease Study. Ophthalmology. 2013 Jun; 120(6):1220–6. 
  20. Hauora M. Review of Children’s Spectacle Subsidy – Final report Wellington, New Zealand: Ministry of Health, 2013.
  21. Sanchez I, Ortiz-Toquero S, Martin R, de Juan V. Advantages, limitations, and diagnostic accuracy of photoscreeners in early detection of amblyopia: a review. Clin Ophthalmol Auckl NZ. 2016; 10:1365–73. 
  22. Williams T, Morgan LA, High R, Suh DW. Critical Assessment of an Ocular Photoscreener. J Pediatr Ophthalmol Strabismus. 2018 May 1; 55(3):194–9. 


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