Automated detection of foveal fixation by use of retinal birefringence scanning

Foveal fixation was monitored in normal subjects remotely and continuously by use of a noninvasive retinal scan. Polarized infrared light was imaged onto the retina and scanned in a 3 degrees annulus at 44 Hz. Reflections were analyzed by differential polarization detection. In all 32 eyes studied, the detected signal was predominantly 88 Hz during central fixation (within +/-1 degree) and 44 Hz during paracentral fixation. Phase shift at 44 Hz correlated with the direction of eye displacement. Potential applications of this technique include screening for eye disease, eye position monitoring during clinical procedures, and use of eye fixation to operate devices.