Precise non-contacting measurement of eye movements using the corneal reflex

Using a real-time, analog, zero-crossing technique, it is possible to locate the centre of the corneal reflex of a collimated infra-red beam accurately. Performance at tracking horizontal eye movements in this manner is similar to contact lens techniques. System noise is less than 30 are sec; dynamic range is 30 arc sec to 36 deg; linearity is 2%; data are currently sampled at 1 kHz; velocity resolution, for a velocity bandwidth of 125 Hz, is 2 deg/sec. With automatic acquisition of the corneal reflex, the subject can be set up for measurement within a 1 min time period. Recordings of residual eye movements of fixation and of a wide range of saccades are comparable with previous findings. Post-saccadic oscillations can be resolved for all sizes of saccades. The amplitude-peak-velocity characteristic of saccades is illustrated.