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Russell J. Adams, James R. Drover, Mary L. Courage; Applied Psychophysics: Estimating the cost of implementing an early vision screening program. Journal of Vision 2007;7(9):534. doi: https://doi.org/10.1167/7.9.534.
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One goal of psychophysics is to apply new knowledge and technologies to real world practical and clinical problems. Due to early CNS plasticity, a longstanding objective within developmental psychophysics is to create “clinic friendly” (simple and rapid) techniques for assessing vision in young children. Recently, new psychophysical methods have emerged for assessing visual acuity, binocular functioning, color vision, and contrast sensitivity. Our laboratory has combined the latest of these with standard optometric procedures (refractive error, ocular alignment/motility) to develop a screening battery for detecting early visual dysfunction. An important issue in such applications is their feasibility, specifically (1) whether tests are valid and (2) whether they are cost effective. Here we provide economic data on the application of this technology. Canadian preschool children (n = 946) were tested with our battery of psychophysical, optical and eye alignment tests, and those who failed any test (n =152) were referred for a gold standard optometric exam. We then calculated measures of clinical validity (sensitivity, specificity, positive/negative predictive value) for each test combination and estimated cost effectiveness ratios (CER) for the most valid combinations (validity [[gt]] 85%). Included in this analysis were determinations of labor, transportation, equipment, materials, and professional fees. We estimated the effectiveness of each test combination to identify a previously undetected child with a vision disorder. CER ranged from $175 to $313 (CAN) per detected child ($1 CAN = $0.88 US). In general, 3-test combinations were most cost-effective ($205 CAN per detected child). Although autorefraction was the most effective single measure, at least one psychophysical test was included in all the best combinations. Our data suggest that given the significant medical and personal costs of failing to detect early visual pathology, vision screening is relatively inexpensive. Moreover, the new psychophysical techniques contribute significantly to the success of pediatric eye screening programs.
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