PURPOSE: To determine whether asymmetrical vergence results in a rotation of Listing's plane independent of vergence-associated changes of eye position in the orbit. METHODS: Six normal subjects were required to fixate on a 3x3 array (40 degrees on a side) of light-emitting diodes arranged on a flat screen 124 cm from the subject. Disparity-induced vergence was elicited with a horizontal Fresnel prism (30 cm/m, approximately 17 degrees) placed in front of one eye. In four subjects accommodative vergence (10 degrees to 15 degrees) was produced by placing a minus spherical lens in front of one eye while the other eye was covered. Eye position was measured binocularly using three-axis search coils. Control data were collected without prisms during monocular and binocular viewing. For all data a planar regression was used to fit torsional eye position as a function of horizontal and vertical position to calculate the horizontal and vertical primary positions that define the orientation of Listing's plane. RESULTS: In the prism experiment, the horizontal primary position of the eye not wearing the prism rotated temporally by 3.9 degrees +/-1.7 degrees compared with the both eyes viewing control condition. The rotation of the prism eye was in a similar range (3.4 degrees +/-2.0 degrees). With accommodation, the horizontal primary position of the viewing eye rotated temporally by 4.4 degrees +/-1.4 degrees compared with the monocular viewing control. In both the accommodation and the prism paradigms there was usually a rotation of vertical primary position downward. CONCLUSIONS: Vergence-induced changes in Listing's plane can be independent of changes in orbital position associated with vergence. This finding supports a role for changes in central innervation in the elaboration of Listing's law.
PURPOSE: To determine whether asymmetrical vergence results in a rotation of Listing's plane independent of vergence-associated changes of eye position in the orbit. METHODS: Six normal subjects were required to fixate on a 3x3 array (40 degrees on a side) of light-emitting diodes arranged on a flat screen 124 cm from the subject. Disparity-induced vergence was elicited with a horizontal Fresnel prism (30 cm/m, approximately 17 degrees) placed in front of one eye. In four subjects accommodative vergence (10 degrees to 15 degrees) was produced by placing a minus spherical lens in front of one eye while the other eye was covered. Eye position was measured binocularly using three-axis search coils. Control data were collected without prisms during monocular and binocular viewing. For all data a planar regression was used to fit torsional eye position as a function of horizontal and vertical position to calculate the horizontal and vertical primary positions that define the orientation of Listing's plane. RESULTS: In the prism experiment, the horizontal primary position of the eye not wearing the prism rotated temporally by 3.9 degrees +/-1.7 degrees compared with the both eyes viewing control condition. The rotation of the prism eye was in a similar range (3.4 degrees +/-2.0 degrees). With accommodation, the horizontal primary position of the viewing eye rotated temporally by 4.4 degrees +/-1.4 degrees compared with the monocular viewing control. In both the accommodation and the prism paradigms there was usually a rotation of vertical primary position downward. CONCLUSIONS: Vergence-induced changes in Listing's plane can be independent of changes in orbital position associated with vergence. This finding supports a role for changes in central innervation in the elaboration of Listing's law.
Authors: Andrzej Grzybowski; Ronald A Schachar; Magdalena Gaca-Wysocka; Ira H Schachar; Farhad Kamangar; Barbara K Pierscionek Journal: Graefes Arch Clin Exp Ophthalmol Date: 2017-11-16 Impact factor: 3.117