Measuring Eye Movements Using The Shape Of The Pupil
Glenn A. Myers, B.T. Wiemann, S.G. Carlson · 2005
We previously described a video based computerized eye monitor [ll to measure gaze angle and pupil area in realtime. This system incorporates windows (both rectangular and circular) under software control to exclude regions outside the windows from being counted as pupil. We demonstrate how to use these windows to measure gaze angle in a way that does not depend upon the details of the position of camera or light source. It may also yield improved accuracy of eye movement measurements for large gaze angles. Previous methods of eye movement measurement, including our own, require careful tracking of the First Purkinje Image (FPI) to compensate for head movement [21. This method results in distortion when the FPI falls on the globe, not on the sclera, as occurs in large gaze angles, or if the camera and/or light source are placed at large angles relative to primary gaze. The new system promises to yield eye movement measurements robust to these problems, and thus to greatly extend the range of applications.