Abstract: A pupil function analyzer has three major subsystems; an electro-optical system, an electronic interface system and a computer/software system. The electro-optical system can, in turn, be described in terms of three subsystems; one that delivers controlled lights to the patient's eyes, another that forms images of the two pupils on a video camera, and a third that moves the optics to maintain alignment with the patient's eyes. The electronic interface system converts signals from the video camera into digital signals to be read by the computer and also responds to the computer to move motors for the maintenance of optical alignment and also operates the light stimuli. The computer/software saves and analyzes the signals sent by the electronic interface, controls the alignment motors, and provides an operator interface, so that the operator can select tests and examine the results.