The purpose of this study was to enhance the performance of steady-state visual evoked potential (SSVEP)-based visual acuity assessment with spatial filtering methods. Using the vertical sinusoidal gratings at six spatial frequency steps as the visual stimuli for 11 subjects, SSVEPs were recorded from six occipital electrodes (O1, Oz, O2, PO3, POz, and PO4). Ten commonly used training-free spatial filtering methods, i.e., native combination (single-electrode), bipolar combination, Laplacian combination, average combination, common average reference (CAR), minimum energy combination (MEC), maximum contrast combination (MCC), canonical correlation analysis (CCA), multivariate synchronization index (MSI), and partial least squares (PLS), were compared for multielectrode signals combination in SSVEP visual acuity assessment by statistical analyses, e.g., Bland-Altman analysis and repeated-measures ANOVA. The SSVEP signal characteristics corresponding to each spatial filtering method were compared, determining the chosen spatial filtering methods of CCA and MSI with a higher performance than the native combination for further signal processing. After the visual acuity threshold estimation criterion, the agreement between the subjective Freiburg Visual Acuity and Contrast Test (FrACT) and SSVEP visual acuity for the native combination (0.253 logMAR), CCA (0.202 logMAR), and MSI (0.208 logMAR) was all good, and the difference between FrACT and SSVEP visual acuity was also all acceptable for the native combination (-0.095 logMAR), CCA (0.039 logMAR), and MSI (-0.080 logMAR), where CCA-based SSVEP visual acuity had the best performance and the native combination had the worst. The study proved that the performance of SSVEP-based visual acuity can be enhanced by spatial filtering methods of CCA and MSI and also recommended CCA as the spatial filtering method for multielectrode signals combination in SSVEP visual acuity assessment.

中文翻译：

---

通过空间过滤增强基于 SSVEP 的视敏度的性能。

本研究的目的是通过空间过滤方法提高基于稳态视觉诱发电位 (SSVEP) 的视力评估的性能。使用六个空间频率步长的垂直正弦光栅作为 11 名受试者的视觉刺激，从六个枕骨电极（O1、Oz、O2、PO3、POz 和 PO4）记录 SSVEP。十种常用的免训练空间滤波方法，即原生组合（单电极）、双极组合、拉普拉斯组合、平均组合、公共平均参考（CAR）、最小能量组合（MEC）、最大对比度组合（MCC）、通过统计分析，比较了 SSVEP 视力评估中多电极信号组合的典型相关分析 (CCA)、多元同步指数 (MSI) 和偏最小二乘法 (PLS)，例如。g.，Bland-Altman 分析和重复测量方差分析。比较了每种空间滤波方法对应的 SSVEP 信号特征，确定了选择的 CCA 和 MSI 空间滤波方法比原生组合具有更高的性能，以进行进一步的信号处理。根据视力阈值估计标准，主观弗莱堡视力和对比度测试 (FrACT) 与原始组合 (0.253 logMAR)、CCA (0.202 logMAR) 和 MSI (0.208 logMAR) 的 SSVEP 视力的一致性均良好, 并且 FrACT 和 SSVEP 视力之间的差异对于原生组合 (-0.095 logMAR)、CCA (0.039 logMAR) 和 MSI (-0.080 logMAR) 也是可以接受的，其中基于 CCA 的 SSVEP 视力具有最佳性能和原生组合的表现最差。