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Geunyoung Yoon; Perceptual evidence of neural adaptation to the eye's habitual aberrations. Journal of Vision 2019;19(15):29. doi: https://doi.org/10.1167/19.15.29.
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© ARVO (1962-2015); The Authors (2016-present)
Visual perception depends on the quality of the eye's optics forming images on the retina and on subsequent neural processes. In eyes with prolonged visual deprivation induced by the abnormally large ocular aberrations, the actual visual performance after precise correction of the aberrations is significantly poorer than that predicted from optical theory and that measured in normal eyes. This unexplained vision loss suggests an interesting long-term interaction between the quality of retinal images and neural processing. The overarching goal of the study is to investigate optical and neural mechanisms underlying long-term adaptation to the habitual optical quality. We use a binocular adaptive optics (AO) vision simulator to fully correct the aberrations in a unique patient group, keratoconus (KC)–a progressive corneal disease causing a normally-developed visual system to suffer severe optical degradation in adulthood. Our studies found that long-term adaptation alters neural processing of both contrast and phase of retinal images. Under AO correction, KC subjects showed abnormal contrast sensitivity, with impaired sensitivity at high spatial frequencies (SF) and enhanced sensitivity at low SFs. It was found that neural adaptation compensates for phase congruency disrupted by eye's aberrations, which attenuates the perceived blur over time. These neural mechanisms also have significant impact on binocular vision such as contrast summation and stereopsis. Our findings suggest that the cortex adapts to imperfect ocular optics, presumably to maximize the efficiency of visual processing and to allow for more veridical perception under natural viewing conditions.
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