Ao. Discenna et al., EVALUATION OF A VIDEO TRACKING DEVICE FOR MEASUREMENT OF HORIZONTAL AND VERTICAL EYE ROTATIONS DURING LOCOMOTION, Journal of neuroscience methods, 58(1-2), 1995, pp. 89-94
We have evaluated a video-based method for measuring binocular horizon
tal and vertical eye movements of human subjects by comparing it with
the magnetic search coil technique. This video tracking system (VTS) u
ses multiple infrared light sources and small video cameras to simulta
neously measure the positions of reflected corneal images and the cent
er of the pupil. The system has a linear range of approximately +/-40
degrees horizontally and +/-30 degrees vertically, a sampling rate of
120 Hz (180 Hz with the head fixed), and system noise with standard de
viation of < 0.04 degrees. The binocular eye-tracking system is light-
weight (190 g), being mounted on goggles that, with the eyes in primar
y position, permit a field of view of 60 degrees horizontally and vert
ically. The VTS is insensitive to translations of the tracker relative
to the eyes. By placing the video preprocessing unit on a cart, eye m
ovements may be recorded while subjects walk through distances up to 1
00 feet. In comparison with the magnetic search coil technique, the VT
S generally provides reliable measurements of horizontal and vertical
eye position; eye velocity is noisier than corresponding coil signals,
but superior to electro-oculography.