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Stephen Engel, Urvi Mistry, Peter Allen; Rapid compensation for defocus in the myopic visual system. Journal of Vision 2017;17(10):498. doi: https://doi.org/10.1167/17.10.498.
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© ARVO (1962-2015); The Authors (2016-present)
When the environment changes, the visual system automatically adjusts its function in order to maintain appropriate behavior. It is unknown, however, to what extent such adaptation effects can be modified by experience. We investigated adaptation to the optical defocus that arises when observers remove their spectacles. We tested whether myopic observers have learned to rapidly compensate for this image blur, which will reduce the retinal contrast of small image features. We compared the myopic observers to ones with normal vision (emmetropes) presented with comparable defocus through blurring lenses. Participants judged the intensity of a small (0.25 deg), dark (5.89 cd/m^2), circle presented on a gray (32.9 cd/m^2) background in an image of an outdoor scene. The small circle was presented for 500 msec following a 500 msec presentation of a large (1 deg) circle, and subjects judged which appeared lighter. The large circle, less affected by blur, was adjusted using a staircase procedure to estimate the apparent luminance of the small circle. For myopic observers (n = 9, mean prescription -2.0D +/- 0.2D), the small circle appeared almost identical in luminance without their glasses as with them (difference was 0.27 cd/m^2, n.s). For emmetropes (n = 8) comparable blur, created by donning +2.0D spectacles, made the circle appear substantially lighter (by 2.09 cd/m^2, p < 0.03). The difference between groups was reliable, t(14) = 2.22, p < 0.05, and arose within a few seconds of exposure to blur. The visual acuity of myopic observers, assessed with a standard eye chart, was also less affected by the blur (0.48 logMAR vs 0.82 logMAR for emmetropes, t(14) = 7.19, p < 0.01). Our results suggest that myopic observers have learned to rapidly compensate for the blur that results when they view the world without correction.
Meeting abstract presented at VSS 2017
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