The Effect of Bilateral Superior Oblique Tenotomy on Primary Position Horizontal Alignment

ABSTRACT

To evaluate the effect of superior oblique tenotomy on horizontal deviation at primary position in A-pattern exotropia with bilateral superior oblique overaction.We performed adjustable strabismus surgeries under topical anesthesia in 6 patients with A-pattern exotropia. After adjusting horizontal deviation to orthotropia in primary position by horizontal muscle surgery, we measured angle deviation in up, primary, downgaze position and added bilateral superior oblique tenotomy, and remeasured the angle deviation at same positions. We analyzed the angle deviation at postoperative one day, one month, and three month in comparison with the preoperative value. There were no change of horizontal deviation in primary position in 2 patients, qhile 3 to 8 prism diopter(PD) esotropic shift occurred in 4 patients(average 3.3PD) after bilateral superior oblique tenotomy at last follow-up of 3 month. At 3 month postoperatively, there was a tendency of exotropic shift from esotropia noted at immediate postoperative period. When combined surgeries of superior oblique and horizontal muscle are considered and intraoperative adjustable surgery is not permitted, horizontal muscle surgery can be performed with disregarding the effect of bilateral superior oblique tenotomy on primary position horizontal alignment.