How does the Eyegaze Edge work?


The Eyegaze Edge is a vision-controlled communication and control system.

  • An Eyegaze user can perform a broad variety of functions including: generating speech, environmental control (lights and appliances), typing, and running both mouse- and keyboard-controlled applications on the Edge screen  Additionally, users can use their Edge as a keyboard and mouse interface for their own computer. Selections are made by looking at boxes or "keys" displayed on the Eyegaze System's screen.

  • Nothing is attached to the user, and a simple 15-second calibration is all that is necessary to begin Eyegaze use.

  • Edge programs vary from simple teaching programs, where the screen is divided into two or four large boxes (keys), to entire on-screen computer keyboards with 75 or more 5/8-inch square keys.

  • Eyegaze users range in age from 3 years to 80 years old.

  • The Eyegaze Edge  is able to accommodate a wide variety of variations in the eye, including droopy eyelids, asymmetric pupils and dry eyes. 

    Without our special "Droopy Eyelid" software many potential users would be eliminated!  Any circumstance that causes part of the pupil to be blocked by the upper or lower eyelid will typically degrade the accuracy of eye-operated systems.

  • The Eyegaze Edge  uses the pupil-center/corneal-reflection method to determine where the user is looking on the screen. An infrared-sensitive video camera, mounted beneath the System's screen, takes 60 pictures per second of the user's eye. A low power, infrared light emitting diode (LED), mounted in the center of the camera's lens illuminates the eye. The LED reflects a small bit of light off the surface of the eye's cornea. The light also shines through the pupil and reflects off of the retina, the back surface of the eye, and causes the pupil to appear white. The bright-pupil effect enhances the camera's image of the pupil so the system's image processing functions can locate the center of the pupil. The Edge calculates the person's gazepoint, i.e., the coordinates of where he is looking on the screen, based on the relative positions of the pupil center and corneal reflection within the video image of the eye. Typically the Eyegaze Edge predicts the gazepoint with an average accuracy of a quarter inch or better.

  • Prior to operating the eyetracking applications, the Eyegaze Edge must learn several physiological properties of a user's eye in order to be able to project his gazepoint accurately. The system learns these properties by performing a calibration procedure. The user calibrates the system by fixing his gaze on a small circle displayed on the screen, and following it as it moves around the screen. The calibration procedure usually takes about 15 seconds, and the user does not need to recalibrate if he moves away from the Eyegaze Edge and returns later.