1. An eye tracking device to be used in a head-worn virtual or augmented reality device, comprising: a virtual content generation subsystem configured to render virtual contents to a user; a plurality of light sources comprising multiple groups of light sources configured to illuminate one eye of the user at least with a pseudorandom pattern, wherein the pseudorandom pattern that comprises a patterned code generated at least by pseudo-randomly varying at least one parameter of one or more groups of the multiple groups of light sources while leaving the at least one parameter of one or more remaining groups of the multiple groups unchanged in a plurality of time slices; an eye tracking device positioned in relation to the one eye of the user and configured to detect one or more characteristics pertaining to an interaction between the light from the one or more groups of the multiple groups of the plurality of light sources and the one eye based in part or in whole upon the pseudorandom pattern; and a processor operatively coupled to the eye tracking device to: determine an eye model representing the one eye of the user with two circular geometric shapes; determine a plurality of eye pointing vectors with the eye model based at least in part upon the one or more characteristics pertaining to the interaction; and determine a movement or a pose of the one eye based at least in part on the plurality of eye pointing vectors and apply the movement or the pose of the one eye as a calculated movement or calculated pose to both eyes.