Determination of eye movements from pupil tracking

Abstract

The human eye is constantly moving even when it is maintaining a stable fixation point. Stable images on the retina rapidly saturate the photoreceptors and fade. The visual system needs of constant stimulation to which it adapts. These constant changes are achieved by fixation micromovements consisting of microtremors, drifts and microsaccades. Thus, accurate determination of pupil center is useful for precise eye tracking. We present a technique for pupil segmentation and contour analysis which will provide valuable information about fixational eye movements. The method is based on fitting an ellipse to the pupil contour. Pupillary hippus, microsaccades and drifts are obtained, as well cyclotorsions.