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Lim et al report a large scale effort to mix home plus health centre acuity screening in preschool children.1 We are very encouraged by the work of Lim et al, particularly concerning the frequency of ocular symptoms in the Korean preschooler, the number of children who were not dismissed from specified follow up (presumed amblyopia risk), and the inclusion of a simple, home administered test which over 97% of children were able to pass. It is of high merit that parents were carefully instructed to place tissue and tape over the non-tested eye, though this does not preclude peeking if the parent is not paying particular attention. Positive answers to the parental questionnaire were not very specific for eye disease and therefore could greatly increase societal cost if used as a screening method. We have a few points of clarification for these authors: How was the home acuity test initially validated? Did a number of children who passed their home exam have gold standard confirmatory exams from which false negative and true negative rates could be estimated? The positive predictive value estimates utilise gold standard exam criteria that need further definition and/or standardisation. (1) It is not clear whether amblyopia was diagnosed at multiple eye clinics and by general or paediatric ophthalmologists, it is not clear what criteria are used to define amblyopia, and the criteria to be included as a “significant” cycloplegic refractive error vastly overestimates risk factors compared to a recently published attempt to standardise reporting of vision screening research.2
We would urge the authors to perform additional calculations on the breakdown of gold standard exam “significant” refractive errors2 and better define how amblyopia was diagnosed.