Ｖｉｄｅｏ‐ｏｃｕｌｏｇｒａｐｈｙ（ＶＯＧ）―眼球運動の三次元解析―

Abstract

There are two methods for measurement of eye position in three dimensions. One is the scleral search coil technique and the other is video-oculography (VOG). Although the VOG system is not as accurate as the scleral search coil system in the ability of time and space resolution, it is suitable for clinical use. There are two types of VOG system: One for analysis using Fick coordinates, and the other for analysis using axis angle, rotation vector and quaternions. Fick coordinate analysis measures three consecutive rotations about the horizontal, vertical, and torsional eye-fixed axes. Axis angle, rotation vector and quaternions measure single axis rotation from a chosen reference position to the current eye position. The system for analyzing by Fick coordinates utilizes the movement of the center of the pupil in order to calculate horizontal and vertical eye movement. In order to calculate the torsional component, the system uses the movement of an iris freckle or iris pattern. The system for analyzing axis angle, rotation vector and quaternions reconstructs the three-dimensional coordinates of the center of the pupil and an iris freckle in space. From these movements in space, the system calculates axis angle, rotation vector and quarternions. In this review, such two type of VOG systems are introduced, and the advantages and disadvantages of both types are discussed.