Hi, first of all I want to state that it is quite sad that you cant get the individual gaze position for each eye, even though it is obviously possible to track individual eyes.
Now to my actual subject. I need the angle between gaze and screen for my application. Would it be a good approach to use the gaze (of the two eyes) and the mean of the two eye positions to create a ray? In other words, is the gaze position from the two eyes derived form the average of the two individual gaze positions?