Accurate three-dimensional eyetracker.

A combined optometer and eyetracking instrument has been developed to measure both the dynamic refractive power and the direction of gaze of the same eye. In effect, this instrument measures, as a function of time, the point in 3-D space on which the eye is fixated. Nothing is attached to the subject (patient), who is easily aligned in the device. The measuring wavelength is in the near ir and is invisible. The usable field of the instrument is greater than 20 degrees ; the horizontal and vertical directions of gaze are measured with a noise level and repeatability of about 1 min of arc. The range of the optometer is approximately -4 to +12 diopters; refractive power is measured to about 0.1 diopter. Two instruments may be aligned side by side for tracking both eyes simultaneously. Three-dimensional monocular and binocular eye movement records are shown.