While humans can detect objects over the entire visual field, we can only see fine detail over a very small portion of the central visual field (corresponding to the fovea/macula area of the retina). This means that when objects are detected in the peripheral field, we have to move our head/ eyes to place the object of interest onto the fovea where it can then be resolved and recognised.
While this is a very efficient design in terms of information processing, it does require a fast and accurate mechanism for moving the head and eyes.
Eye position is determined by a complex balancing act performed by the six extra-ocular muscles under the control of a complex neural network in the brain. There is a huge literature describing the anatomy, physiology, neurology and psychology of eye movements and it is strongly recommended that users of the Clinical Eye Tracking system familiarise themselves with this literature.
The purpose of this manual is to describe the application of the Clinical Eye Tracker – it is the responsibility of the user to ensure that the instrument is used properly and the results are interpreted appropriately.