[Surgical effect on incomitance of vertical deviation in superior oblique palsy measured by a synoptometer]

Using a synoptometer we evaluated the surgical effect on the incomitance of the vertical deviation in 26 patients with congenital superior oblique palsy. Either an inferior oblique recession or a superior oblique plication was performed. The two operative procedures reduced the incomitance caused by horizontal change of gaze, but produced incomitance by the vertical change of gaze and the incomitance increased proportionately with change of gaze from down to upward positions, which was not recognized preoperatively. As a result, the hyperdeviation was markedly reduced in the field of action of the overacting inferior oblique muscle. Moreover the surgical effect on the incomitance of the vertical deviation was studied in 13 patients with acquired superior oblique palsy treated with superior oblique plication. This procedure increased not only the incomitance in the upward positions by horizontal change of gaze, but also produced incomitance in adductive positions by vertical change of gaze. Therefore the hyperdeviation of the paretic eye was remarkably overcorrected in the field of action of the antagonist of the paretic superior oblique muscle.