Modifications and Violations
Listing's law is not obeyed when the eyes counter-rotate during head rotation to maintain gaze stability, either due to the Vestibulo-ocular reflex (VOR) or the optokinetic reflex. Here the eye simply rotates about approximately the same axis as the head (which could even be a pure torsional rotation). This generally results in slow movements that drive the eye torsionally out of Listing's plane. However, when the head translates without rotating, gaze direction remains stable but Listing's law is still maintained.
Listing's law persists but takes on a torsional bias when the head is held at a tilted posture and the eyes counter-roll, and when the head is held steady upward or downward Listing's plane tilts slightly in the opposite direction when.
The Listing's planes of the two eyes tilt outward, opposite to the eyes, when they converge on a near target.
When larger 'gaze saccades' are accompanied by a head movement, Listing's law cannot be maintained constantly because VOR movements occur during or toward the end of the movement sequence. In this case, saccades take on torsional components equal and opposite to the oncoming torsional movements such that Listing's law is transiently violated, but the eye ends up at zero torsion in the end.
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