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PandAcuity in paediatrics: a novel clinical measure of visual function based on the panda illusion
  1. Carina Kelbsch1,
  2. Bettina Spieth1,
  3. Eberhart Zrenner2,3,
  4. Dorothea Besch1,
  5. Torsten Straßer1,3
  1. 1University Eye Hospital Tuebingen, University of Tuebingen, Tuebingen, Germany
  2. 2Werner Reichardt Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany
  3. 3Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
  1. Correspondence to Dr. sc. hum. Torsten Straßer, Institute for Ophthalmic Research, University of Tübingen, Tübingen 72076, Germany; torsten.strasser{at}


Background/aims To evaluate the PandAcuity test for visual function testing in a paediatric cohort and to examine its agreement with conventional visual acuity (VA) testing.

Methods PandAcuity scores were determined in 152 children (77 males) aged between 3 and 15 years after VA testing (LEATM-test, E-chart, Landolt-C-rings or numbers). The PandAcuity test consisted of illusions made up from silhouettes of animals ‘hidden’ within zig-zag-patterns of decreasing spatial frequencies. Correlation analyses between PandAcuity score and VA were performed.

Results 150 children completed the test in at least one eye, 148 in both eyes. The PandAcuity test demonstrated good test–retest reliability (intraclass correlation coefficient=0.89) between two runs. VA and PandAcuity score showed a medium to large correlation (Spearman’s ρ=0.52, p<0.0001). 93% of the children’s visual impairment was classified in the same range by both test types. Receiver operating characteristic analysis of predicted visual impairment showed an excellent agreement with the classification based on VA testing (AUC=0.84).

Conclusion The PandAcuity test is rapid, simple and well accepted, rendering it a suitable supplement for the clinical assessment of VA in children. Because of its counterintuitive application (a higher number of correctly identified images means worse VA), it can be used to cross-validate conventional acuity tests to assure children’s compliance.

  • child health (paediatrics)
  • diagnostic tests/Investigation
  • psychophysics
  • vision
  • visual perception

Data availability statement

Data are available on reasonable request.

Statistics from


  • Contributors TS, CK and BS: conception and design of the work; BS: acquisition of the data; TS and CK: analysis of the data; TS, CK, DB and EZ: interpretation of the work; TS, CK, DB and EZ: revising the work. All authors have approved the version to be published and agreed to be accountable for all aspects of the work. TS acts as guarantor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests EZ and TS filled a patent for using the panda illusion for the refraction of the eye.

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

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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