Relationship between subjective spherical power and estimated power by SSVEP

Abstract

Purpose : Steady-State Visual Evoked Potential (SSVEP) is an Electroencephalograms (EEG) signal synchronized with the flickering frequency of the visual stimulus. It is known that the power of SSVEP is to be stronger when visual stimuli are properly visible. Some studies measure visual acuity by SSVEP. However, as we know, few papers discuss the estimated spherical power by the examinee’s subjective refraction by SSVEP. The purpose of this study is to elucidate the relationship between spherical power by the examinee’s subjective refraction and estimated power by SSVEP.

Methods : There are 14 participants in the experiment. Participants were seated 5[m] in front of the display. The experiment is performed with one right eye and one left eye. Participants gaze at a cross on the center of the checkerboard for 10 seconds. The number of checkerboard grids is 5×5 and the flickering frequency is 15[Hz]. Fog is added to the spherical power by the participant’s objective refraction. Fog is changed every -0.25[D] from +2.00[D] to -0.50[D]. Then, fog is changed every -0.50[D] to F_d-2.00[D]. F_d is the diopter when participants cannot see the checkerboard. We record the EEG signals and focus on O1, O2, and Oz electrodes. We obtain the power of SSVEP by Fourier transform.

Results : Fig.1 is the power of SSVEP in S10's left eye. We focus on “the spherical power where SSVEP was first detected" and “the spherical power where the power of SSVEP is maximum value" for participants. "SSVEP is detected" means that the power in 15[Hz] is over μ+2σ. μ is the mean of power between 14 and 16[Hz]. σ is the standard deviation of the power value between 14 and 16[Hz]. We also focus on a combination of these spherical powers. Fig.2 is a scatter plot. The horizontal axis is the spherical power by the examinee’s subjective refraction. The vertical axis is the spherical power focused on the maximum value of 15[Hz] from spherical power where SSVEP was first detected to -2.00[D]. The red lines in Fig.2, are regression lines, and the red dotted line is the 95% confidence interval. From Fig.2, the coefficient of determination is 0.8167 and the maximum value of 15[Hz] is observed near the subjective refraction value.

Conclusions : We showed the relationship between spherical power by the examinee’s subjective refraction and estimated power by SSVEP.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Power of SSVEP in S10's left eye

 

Scatter plot between subjective spherical power and estimated power by SSVEP