An eye-tracking device with combined retinal and anterior eye-tracking capabilities

Understanding how the eye moves is of utmost importance to scientists in neurology, ophthalmology, cognitive sciences, and medicine. Popular eye trackers observe the anterior parts of the eye, but a new class of eye-trackers looks at the retina. Each of the two techniques has advantages and disadvantages: the anterior eye trackers provide data with low precision but high accuracy, while retinal eye trackers provide data with high precision but low accuracy. We have built a device that combines the two trackers and allows for the simultaneous acquisition of eye motion on the anterior and posterior parts of the eye during visual tasks displayed to the subject, such as fixations, saccades, and smooth pursuit. The retinal tracker is based on the concept of SLO, but modified to acquire small image frames (5deg x 3deg) at high speeds. The anterior tracker uses a CMOS camera to register the pupil and the Purkinje reflections.