[The effect of weakening the overaction superior oblique muscles on the status of ocular torsion].

Objective: To investigate the effect of weakening the superior oblique muscles on the status of ocular torsion.

Methods: Twenty-nine patients (58 eyes) underwent tenotomy or partial ectomy of bilateral superior oblique muscles for treatment of superior oblique overacting. Objective cyclodeviations were assessed by fundus photograph before and 7 days after the surgery. The photographs were transferred to a computer and then the fovea-disc angle was measured by a software for drawing pictures. Subjective cyclodeviations and binocular vision function were assessed by synoptophore.

Results: Fundus photography before surgery revealed that the intorsion was 10.48 degrees +/- 6.01 degrees for the right eye and was 9.37 degrees +/- 5.88 degrees for the left eye. The reduction of the cyclodeviations by weakening the superior oblique muscle for the right and left eye was 9.11 degrees +/- 7.09 degrees and 7.94 degrees +/- 4.76 degrees respectively. The comparisons of objective ocular torsion for both eyes showed high significant differences (P < 0.01) pre- and post-operatively. There were no significant differences (P > 0.05) between the effects of tenotomy or partial ectomy of bilateral superior oblique muscles. All patients showed no cyclotropia and normal binocular vision function was obtained with synoptophore before and after surgery.

Conclusions: Weakening the overaction superior oblique could correct ocular incyclodeviation. Both tenotomy and partial ectomy of bilateral superior oblique muscles can treat ocular incyclodeviation effectively. The changes of subjective and objective cyclodeviations are inconsistent with each other.