Discrete eye-position recording for alternative communication.

A feasibility study for using Electro-Oculo-Graphy in a two-step direct-selection type of communication is carried out. The magnitude of any saccade at a certain adjustable time Ts after the start of the saccade is measured and compared to a number of previously adjusted set reference potentials by a multicomparator. Any E.O.G. signal within a certain range is classified to have the central reference-potential of a band. Once the corresponding potential band is determined, a light source will light up, serving as a visual feed-back. The automatic reset circuit will keep the potential of the E.O.G. signal at the central reference potential as long as the eye stays 'fixed' on the same light source in the column of light sources. Slow pursuit movement of the eye and/or the head are possible however below the trigger-velocity on any saccade before the selection of another light source, giving the user a certain degree of freedom. It is concluded, that the construction of a two-step E.O.G. controlled communicator by direct selection with discrete vertical eye-positions is a possible approach. Application of the saccade-discretisator to the field of rehabilitation is discussed.

Optical communication aids in rehabilitation.

Two types of low-cost optical communication aids for non-vocal paralyzed patients are described: one based on reflection via mirrors and the other based on refraction via prisms. The recognition by the partner, when the handicapped person looks straight via the mirror/prism into his eyes, is crucial in the selection of the corresponding symbol in this communication process. The configurations in which the mirrors/prisms are arranged in aids of one- or two-dimensions, respectively. Preceding the choice of an advanced eye-controlled aid, eye defects can be detected using two-dimensional aids. Both types of optical communicators have been used in rehabilitation. The prism-aids appeared to be preferable to mirror-devices and to ETRAN-window in the communication process for speech replacement or in playing simple games.