1. A method for determining gaze in a near-eye mixed reality display device comprising: determining boundaries of a three dimensional gaze detection coordinate system for each eye based on positions of glints detected on the respective eye, positions on the near-eye display device of illuminators for generating the glints, and a position of at least one sensor for capturing reflected eye data of the respective eye from which the positions of glints are detected; automatically checking periodically the reflected eye data for any change along a depth axis of the gaze detection coordinate system, the depth axis extending from a respective display optical system of the near-eye, mixed reality display device toward the respective eye; responsive to detecting any change along at least one depth axis, triggering redetermination of the boundaries of the three dimensional gaze detection coordinate system; determining a gaze vector for each eye based on reflected eye data including the glints and the boundaries of the three dimensional gaze detection coordinate system; determining a point of gaze based on the gaze vectors for the eyes in a three-dimensional (3D) user field of view of the near-eye mixed reality display device including real and virtual objects; and identifying any object at the point of gaze in the 3D user field of view.