Although a number of devices for monitoring eye position information are available commercially, none that are relatively inexpensive afford a high degree of accuracy, spatial resolution, and temporal resolution. Q-T Products, Inc. has taken advantage of recent advances in diode array technology in constructing a two dimensional eye tracker that will allow a sampling rate of 1 KHz, spatial resolution of 6 min, and accuracy of 10 min. It is currently estimated that the retail cost of a tracker with the above specifications would range between $15,000 and $20,000.One of the standard features offered with the tracker will be a software implemented calibration routine written in the assembly languages of a variety of computers. When used with any individual, the result will be the creation of a unique look-up table that, in conjunction with a real-time interpolation algorithm, can translate horizontal and vertical eye positions defined in an arbitrary space, into horizontal and vertical eye postions defined in visual space. The specific goal of the proposed Phase I project is to empirically compare two calibration routines with respect to their accuracy, and choose one or some combination of both as the routine to be offered.National Eye Institute (NEI)