Hi,
Sorry for the confusion.
The Eye position that the eyetracker hands out refers to an internal state parameter that does not translate “exactly” to a physical point, but can for all purposes be thought of, and follows the behaviour, of the centre of the pupil. i.e NOT the centre of the eyeball.
The coordinate system is righthanded and the origo of the coordinate system is at the centre of the screen with y and x axis in the plane of the screen and z pointing towards the user.
Hope this helps,
Mattias