October 2020
Volume 20, Issue 11
Open Access
Vision Sciences Society Annual Meeting Abstract  |   October 2020
Rapid, precise and objective visual acuity assessment method by combining FrACT and SSMVEPs
Author Affiliations & Notes
  • Xiaowei Zheng
    Xian Jiaotong University, China
  • Guanghua Xu
    Xian Jiaotong University, China
  • Yongcheng Wu
    Xian Jiaotong University, China
  • Yuhui Du
    Xian Jiaotong University, China
  • Renghao Liang
    Xian Jiaotong University, China
  • Sicong Zhang
    Xian Jiaotong University, China
  • Kai Zhang
    Xian Jiaotong University, China
  • Footnotes
    Acknowledgements  Supported by grants from the Independent Innovation Capacity Improvement Project of Xi’an Jiaotong University (PY3A071) and the National Natural Science Foundation of China (NSFC-51775415).
Journal of Vision October 2020, Vol.20, 989. doi:https://doi.org/10.1167/jov.20.11.989
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      Xiaowei Zheng, Guanghua Xu, Yongcheng Wu, Yuhui Du, Renghao Liang, Sicong Zhang, Kai Zhang; Rapid, precise and objective visual acuity assessment method by combining FrACT and SSMVEPs. Journal of Vision 2020;20(11):989. https://doi.org/10.1167/jov.20.11.989.

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      © ARVO (1962-2015); The Authors (2016-present)

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Traditional visual acuity test depends on the subjective evaluation, such as the naming of Snellen letters, which is difficult to perform with preverbal children and even adults with suspected malingering or low intellectual abilities. Although steady-state motion visual evoked potentials (SSMVEPs) can provide an objective visual acuity assessment method (Zheng et al., 2019), the time spent on the visual acuity test is a bit long and the spatial frequencies of stimulus are limited, easily leading to visual fatigue and affecting the precision of results. Hence, the combination of the Freiburg Visual Acuity and Contrast Test (FrACT) and SSMVEPs provides an alternative method for rapid and precise visual acuity assessment (Bach, 1996). In this study, we replaced the Landolt-Cs of eight orientations of FrACT with SSMVEP paradigms of eight different temporal frequencies, and the manual response by pressing the buttons of the response box was also replaced by automatic online SSMVEP response by canonical correlation analysis (CCA) method. The visual acuity was defined as the corresponding spatial frequency threshold of the paradigm at the steepest part of the psychometric function of a logistic function (Bach, 2006), and the best PEST (parameter estimation by sequential testing) was used to estimate threshold by using previous response results (Lieberman & Pentland, 1982). Ten subjects participated in this experiment for two minutes of one eye’s test, and Bland-Altman analysis found that the agreement between objective SSMVEP and subjective FrACT visual acuity was pretty good. Our study proved that the visual acuity assessment based on the combination of SSMVEPs and FrACT can be an objective, rapid and precise method to measure visual acuity, especially for infants and preverbal children.


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