Numerical Confusion Errors in Ishihara Testing: Findings From a Population-based Study - 18/08/11

Doi : 10.1016/j.ajo.2005.01.002

Michael Cosstick, BAppSc ^a,^b, Dana Robaei, MBBS, MPH ^a, Kathryn Rose, PhD ^b, Elena Rochtchina, BSc, MAppStat ^a, Paul Mitchell, MD, PD ^a,^⁎ : FRANZCO
^a Department of Ophthalmology Centre for Vision Research, Westmead Hospital) and Westmead Millennium Institute; University of Sydney, Westmead, Australia.
^b School of Applied Vision Sciences, Faculty of Health Sciences, University of Sydney, Westmead, Australia.

Inquires to Professor Paul Mitchell, MD, PhD, FRANZCO, Department of Ophthalmology, Center for Vision Research, University of Sydney, Westmead Hospital, Hawkesbury Road, Westmead, NSW, Australia, 2145; fax: (+61) 2-9845-8345

Résumé

Purpose

To describe the prevalence of numerical confusion errors in Ishihara testing in a representative sample of Australian children.

Design

Cross-sectional, population-based study.

Methods

The Sydney Myopia Study examined a representative stratified random cluster sample of 1,741 children (aged 6 years) attending 34 schools in Sydney, Australia (response rate, 78.9%), including color vision tests in 1,735 children. Those with any color vision defects (n = 33; 1.9%; 97% boys) were excluded. Responses for each Ishihara plate were recorded.

Results

Numerical confusion errors were made by 75.8% of children with normal color vision; there was no gender difference. Plates 3 and 7 were particularly prone to numerical confusion errors; 48.4% and 40.8%, respectively, of children misread these plates.

Conclusion

Numerical confusion errors in the Ishihara test were relatively common in children with normal color vision. The frequency of such errors could indicate an inherent deficiency in this commonly used test.

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The Sydney Myopia Study is supported by the National Health & Medical Research Council (grant 253732) and the Westmead Millennium Institute, University of Sydney.