Reliability of Measurement of Subjective Visual Vertical Using Original Software Developed for Healthy Adults

Abstract

[Purpose] The purpose of this study was to clarify the reliability of measurement of subjective visual vertical (SVV) using original software developed for healthy adults. [Subjects and Methods] Twelve healthy adults participated in this study. SVV was measured using the software. For the measurement of SVV, a luminous rod was presented on a computer screen at eye level to the seated subjects. The luminous rod was rotated in the coronal plane until the subject sensed it was vertical. The mean value of eight trials was calculated. One physical therapist evaluated SVV at the beginning of the study and one week later. The intra-class reliability (ICC) and measurement error of the 95% confidence interval of the minimal detectable change (MDC₉₅) were used to estimate the reliability. [Results] The intra-examiner reliability estimates ranged from 0.8-0.9. MDC₉₅ of the SVV measurements were 0.7-0.8°. [Conclusion] The results suggest that the measurement of SVV using the software is highly reliable.