Eye tracking white sclera (limbus tracking). It presents another challenge for vertical eye movements due to obstruction of eyelids. Eye-tracking setups vary greatly: some are head-mounted, some require the head to be stable (for example, with a chin rest), and some function remotely and automatically track the head during motion. Most use a sampling rate of at least 30 Hz. Although 50/60 Hz is more common, today many video-based eye trackers run at 240, 350 or even 1000/1250 Hz, speeds needed in order to capture fixational eye movements or correctly measure saccade dynamics. Eye movements are typically divided into fixations and saccades
Book of the Ten Treatises of the Eye means for medieval ophthalmologists in the West to come into contact with the work of Galen. There are four essential doctrines that shape Hunayn's dissertation on vision and the anatomy of the eye: Hunayn relies on these principles to build up his conception of vision, which incorporates the anatomy of the eye in a way that makes discussion of one without the other unproductive. The structure of the eye is presented as a hierarchy, starting first with the part that is most directly responsible for sight, and working down towards the parts which exists only to facilitate this function. The