The Study for the Velocity Measurement of the Horizontal Saccadic Eye Movement

ABSTRACT

Saccadic eye movement may be difined entirely on the basis of velocity-amplitude characteristics. Despite the obvious importance of saccadic peak velocity measurements, there is lack of agreement about saccadic velocity-amplitude relationships in general and particularly with regard to the direction of movement. The variability of the results is attributed mostly to different recording techniques used and partly to the sample size. The aim of this study is to investigate the effect of saccadic direction for the determination of their possible influence upon the horizontal saccadic peak velocity. Therefore, six basic patterns of horizontal saccadic movement were determined and the direction and velocity of these basic patterns of the angular distance of 10 degrees were recorded and discussed. The experimental apparatus consisted of Biometrics Eye Movement Monitors, target function generators, oscillographic recorders and the other fixation devices. The experimental subjects were three healthy Korean adults. All experiments had been performed in the dark room for 4 weeks. The position and peak velocity of saccadic eye movement in the records were carefully observed and the data were analyzed statistically for significant change with the use of t-test at the 5 per cent level and the main results are as follows: 1. In the horizontal saccadic eye movement in the angular distance of 10 degrees, the production rate of undershoot or corrective movement is low and most of the saccadic eye movement are normal. 2. The mean of the saccadic peak velocity is 295.6 deg/sec in the angular distance of 10 degrees. 3. The mean horizontal saccadic peak velocity is faster in the nasal direction, as compared with the temporal direction, but the difference is not statistically significant. 4. The mean saccadic peak velocity is greater in the nasal than in the temporal direction among the velocities of the centering, decentering and symmetry but the difference is not statistically significant. 5. The analysis of the results showed that the mean horizontal saccadic peak velocity has no statistically significant difference between the nasal and the temporal direction in the angular distance of 10 degrees. Author feels that the methods and results of this study may be useful tools in the diagnosis and research of eye disease related to the nervous system and that further study to establish the standard data of saccadic peak velocity should be performed at the various angular distances.