The Optokinetic Nystagmus Indicates Functional State Changes: VR Study

The purpose of this work was to study the relationship between the features of optokinetic nystagmus and changes in the functional state of a person during observation of rotation in virtual reality. The following hypothesis has been proposed: during the changes in functional state under optokinetic stimulation, slow phases of nystagmus will be longer than during moments of functional state stability. The experiment involved 10 subjects. A virtual optokinetic drum rotating around vertical axis in a horizontal plane at a speed of 30, 45 and 60 degrees per second was used for stimulation. The stimulation was demonstrated using virtual reality system HTC Vive Pro Eye. The analyzed parameters included the relative duration of the slow phase of OKN, the overall score of the “Simulator Sickness Questionnaire”, and the subjective perception of the own state. It was found that with an increase in rotation speed, the overall score of the questionnaire and the subjective perception of the changes in functional state also increased. It was also found that the optokinetic nystagmus slow phases duration increases during the functional state instability, which can be explained by the phenomenon of “nystagmus fading,” which occurs due to eye muscle fatigue.