Measuring torsional eye movements by tracking stable iris features

We propose a new method to measure torsional eye movements from videos taken of the eye. In this method, we track iris features that have been identified as Maximally Stable Volumes. These features, which are stable over time, are dark regions with bright borders that are steep in intensity. The advantage of Maximally Stable Volumes is that they are robust to nonuniform illumination and to large changes in eye and camera position. The method performs well even when the iris is partially occluded by reflections or eyelids, and is faster than cross-correlation. In addition, it is possible to use the method on videos of macaque eyes taken in the infrared, where the iris appears almost featureless.