Fig. 5.

Plot of horizontal eye position versus torsional eye position, either with head upright or with head tilted 45° to the right. The horizontal eye position was taken directly from the EyeSeeCam software, while the torsional eye position was calculated using the method described in the text. In both head positions, the eye positions lie roughly in a plane (“Listing's plane”). Note that the view here is not perfectly along the best fit plane. The torsional counter-roll of the eyes is clearly visible as a shift along the torsion axis.