Eye tracking using aspheric cornea model

A display system configured to project light to an eye of a user to display virtual image content in a vision field of said user, said eye having a cornea and a pupil, said display system comprising:

• a frame configured to be supported on a head of the user;
• a head-mounted display disposed on the frame, said display configured to project light into said user's eye to display virtual image content to the user's vision field;
• one or more eye tracking cameras configured to image the user's eye;
• a plurality of light emitters;
• and
• processing electronics in communication with the display and the one or more eye tracking cameras, the processing electronics configured to:
• receive images of the user's eye captured by the one or more eye tracking cameras, wherein glint reflections of the different light emitters are observable in said images of the eye captured by the one or more eye tracking cameras;
• and
• estimate a location of a corneal center of the user's eye based at least in part on the locations of the glint reflections in said images captured by said one or more eye tracking cameras,
• wherein said processing electronics employ an aspheric model of said cornea in numerical calculations to estimate said location of said corneal center of the user's eye,
• wherein said processing electronics additionally employ a spherical model of said cornea in further numerical calculations to estimate said location of said corneal center, and
• wherein said estimate of said corneal center determined from a spherical model of said cornea is applied to said aspheric model in the numerical calculations to determine a location of said corneal center.