A communication instrument has been developed for use by a quadriplegic person who is limited solely to eye motion as a control input. The instrument uses an infrared-emitting diode/phototransistor sensor mounted on the frame of a pair of eyeglasses to transform deliberate lateral eye motion into a contact-closure output form. A software program has also been developed for use with this instrument to display letters of the alphabet in a series of six lines. The lines are slowly scrolled until the desired line is reached, then stopped by a lateral eye motion. The scrolling then continues for each character in that line until the desired character is reached. Again, lateral eye movement causes the scrolling to stop and the character becomes part of a string. This process continues until a command character is selected whereby the string can be sent to a printer, spoken through a speech synthesizer, or erased.