PandAcuity in paediatrics: a novel clinical measure of visual function based on the panda illusion

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 (LEA(TM)-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.