ABSTRACT
A number of measurement techniques have been used to determine the torsional component of eye position, like afterimage, methods using the blind spot or the axis of astigmatism, search coils, and video-images. The dual search coil technique allows eye position recordings with very high temporal and spatial resolution. The orientation and movement of the eye within the head can be calculated from the orientation of the head and of the eye with respect to the magnetic field. In the one-dimensional analysis of eye movements, eye velocity is simply given by the time derivative of eye position. The error which is induced if one ignores the eye position and simply takes the time-derivative of the eye position to be the eye velocity is maximal if the eye velocity is perpendicular to the current eye position. The standard technology for measuring three-dimensional eye movements is currently the scleral search coil technique.
