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Lisa Cruz, Brian Keane, Sabine Kastner, Thomas Papathomas, Steven Silverstein; Optically correcting visual acuity beyond 20/20 improves visual perception: A cautionary tale for studies of special populations. Journal of Vision 2016;16(12):241. doi: https://doi.org/10.1167/16.12.241.
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© ARVO (1962-2015); The Authors (2016-present)
Background. The vast majority of studies that examine visual processing in special populations ensure that subjects have normal or corrected-to-normal vision, without also reporting whether subject groups are matched on visual acuity (VA) within the normal range. This is problematic because a host of factors impact VA (e.g., aging, schizophrenia) and because optimal VA among healthy adults is better than 20/20. Therefore, we ask: Does refractive error within the normal range alter visual performance? Methods. Ten healthy adults with 20/20 uncorrected binocular VA performed three perceptual tasks—once without eyeglasses and once with eyeglasses so that they could read an additional line (0.11 logMAR units) on a logarithmic eye chart. In the contour integration (CI) task, subjects located an integrated shape embedded in varying quantities of randomly-oriented noise elements; in the collinear facilitation (CF) task, subjects detected a low-contrast element flanked by collinear or orthogonal high-contrast elements; in the discrimination task, subjects discerned the orientation of four briefly-presented, high-contrast pac-man elements. Spatial frequency was modulated in the CI and CF tasks (4-12 cycles/deg) by scaling the entire display. Results. Optical correction enabled observers to integrate contours under noisier conditions (p=.008), detect elements of lower contrast (p=.001) and discriminate orientation differences of smaller magnitude (p=.04). When elements were composed of high (rather than lower) spatial frequency, optical correction conferred a greater benefit for contour integration (p=.003) and a marginally greater benefit for contrast sensitivity (p=.07). Conclusions. Previous studies reporting contour integration, contrast sensitivity, or orientation discrimination effects in aging, development, or psychiatric disorders may need to be re-evaluated if they did not match for VA within the normal range. Our results also offer a surprisingly powerful explanation of individual differences and show that modest reductions in refractive error within the normal range strongly improve visual perception.
Meeting abstract presented at VSS 2016
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