PURPOSE. As a normal subject looks from far to near, Listing's plane rotates temporally in each eye. Since Listing's plane relates to the control of torsional eye position, mostly by the oblique eye muscles, the current study was conducted to test the hypothesis that a patient with isolated superior oblique palsy would have a problem controlling Listing's plane. METHOD. Using the three-dimensional scleral search coil technique, binocular Listing's plane was measured in four patients with congenital and in four patients with acquired unilateral superior oblique palsy during far-(94 cm) and near-(15 cm) viewing. The results were compared to previously published Listing's plane data collected under exactly the same conditions from 10 normal subjects. RESULTS. In patients with unilateral superior oblique palsy, either congenital or acquired, Listing's plane in the normal eye rotated temporally on near-viewing, as in normal subjects, while in the paretic eye it failed to do so. In patients with acquired superior oblique palsy, Listing's plane was already rotated temporally during far-viewing and failed to rotate any farther on near-viewing, whereas in patients with congenital superior oblique palsy Listing's plane in the paretic eye was oriented normally during far-viewing and failed to rotate any farther on near-viewing. CONCLUSIONS. These results suggest that the superior oblique muscle, at least in part, is responsible for the temporal rotation of Listing's plane that occurs in normal subjects on convergence. (Invest Ophthalmol Vis Sci. 2004;45:3043-3047) DOI:10.1167/iovs.04-0014 A lthough the eye can rotate with three degrees of freedom, during visual fixation, smooth pursuit, and saccades, it exercises only two: horizontal and vertical. Furthermore, when the head is not moving and there is no vestibular input, horizontal and vertical eye-in-head position (gaze position) determines how much the eye has rotated about its line of sight (i.e., the amount of torsion). This relationship between torsional eye position and gaze position is described by Listing's law. During visual fixation, smooth pursuit, 1 and saccades, 2 Listing's law correctly predicts that the tips of the rotation vectors used to describe eye positions all lie in a plane called the displacement plane. 3 The displacement plane is determined by Listing's plane (LP), which is head fixed and changes orientation under few conditions. For example, LP changes orientation during prolonged fusion of an imposed vertical disparity 4 and during prismatically induced horizontal and vertical vergence. 6 -9 LP rotates in each eye around a point that is not at the origin of the coordinate system describing eye position. Consequently, it is only during downward gaze that torsional eye position changes significantly on near-viewing. Temporal rotation of LP on near-viewing approximately aligns the three-dimensional eye rotation axes during saccades and, as a consequence, eye eccentricity is minimized. 11 However, another line of evidence suggests that the vergence-mediated change in LP may be due to relaxation of one extraocular muscle, the superior oblique. Eye torsion is produced mainly by the oblique eye muscles. There could be some structural differences between congenital and acquired SOPs. One study reported imaging of abnormalities of the superior oblique tendon in congenital SOP in contrast to atrophy of the superior oblique muscle in acquired SOP, 15 but this result was not replicated
