Xiaowei Zheng1, Guanghua Xu2, Chenghang Du3, Wenqiang Yan4, Peiyuan Tian1, Kai Zhang5, Renghao Liang6, Chengcheng Han7, Sicong Zhang7. 1. School of Mechanical Engineering, Xi'an Jiaotong University, Building West NO. 5, Yanxiang Road NO. 99, Xi'an, 710049, CHINA. 2. School of Mechanical Engineering, Xi'an Jiaotong University, XIANNING WEST ROAD XI'AN, Shaanxi, CN, Xi'an, Shaanxi, 710049, CHINA. 3. Xi'an Jiaotong University, XIANNING WEST ROAD, XI'AN, Shaanxi, 710049, CHINA. 4. School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China, XIANNING WEST ROAD, XI'AN, SHAANXI, 710049, CHINA. 5. School of Mechanical Engineering, Xi'an Jiaotong University, Xianning West Road, Beilin District, NO.28, Xi'an, Shaanxi, 710000, CHINA. 6. School of Mechanical Engineering, Xi'an Jiaotong University, XIANNING WEST ROAD XI'AN, SHAANXI, Xi'an, Shaanxi, 710049, CHINA. 7. School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, P.R. China, Building West NO. 5, Yanxiang Road NO. 99, Xi'an, 710054, CHINA.
Abstract
OBJECTIVE: This study aimed to explore an online, real-time, and precise method to assess steady-state visual evoked potential (SSVEP)-based visual acuity more rapidly and objectively with self-adaptive spatial frequency steps. APPROACH: Taking the vertical sinusoidal reversal gratings with different spatial frequencies and temporal frequencies as the visual stimuli, according to the psychometric function for visual acuity assessment, a self-adaptive procedure, the best parameter estimation by sequential testing (PEST) algorithm, was used to calculate the spatial frequency sequence based on all the previous spatial frequencies and their significance of the SSVEP response. Simultaneously, the canonical correlation analysis (CCA) method with a signal-to-noise ratio (SNR) significance detection criterion was used to judge the significance of the SSVEP response. MAIN RESULTS: After 18 iterative trails, the spatial frequency to be presented converged to a value, which was exactly defined as the SSVEP visual acuity threshold. Our results indicated that this SSVEP acuity had a good agreement and correlation with subjective Freiburg Visual Acuity and Contrast Test (FrACT) acuity, and the test-retest repeatability was also good. SIGNIFICANCE: The self-adaptive step SSVEP procedure combined with the CCA method and SNR significance detection criterion appears to be an alternative method in the real-time SSVEP acuity test to obtain objective visual acuity more rapidly and precisely.
OBJECTIVE: This study aimed to explore an online, real-time, and precise method to assess steady-state visual evoked potential (SSVEP)-based visual acuity more rapidly and objectively with self-adaptive spatial frequency steps. APPROACH: Taking the vertical sinusoidal reversal gratings with different spatial frequencies and temporal frequencies as the visual stimuli, according to the psychometric function for visual acuity assessment, a self-adaptive procedure, the best parameter estimation by sequential testing (PEST) algorithm, was used to calculate the spatial frequency sequence based on all the previous spatial frequencies and their significance of the SSVEP response. Simultaneously, the canonical correlation analysis (CCA) method with a signal-to-noise ratio (SNR) significance detection criterion was used to judge the significance of the SSVEP response. MAIN RESULTS: After 18 iterative trails, the spatial frequency to be presented converged to a value, which was exactly defined as the SSVEP visual acuity threshold. Our results indicated that this SSVEP acuity had a good agreement and correlation with subjective Freiburg Visual Acuity and Contrast Test (FrACT) acuity, and the test-retest repeatability was also good. SIGNIFICANCE: The self-adaptive step SSVEP procedure combined with the CCA method and SNR significance detection criterion appears to be an alternative method in the real-time SSVEP acuity test to obtain objective visual acuity more rapidly and precisely.