Intraoperative monitoring of torsion to prevent vertical deviations during augmented vertical rectus transposition surgery

BACKGROUND Total transposition of the superior and inferior rectus muscle laterally, with augmentation sutures, may be complicated by induction of an undesirable vertical deviation. Induced vertical misalignment may be associated with changes in torsion. We have developed a simple method to monitor intraoperative torsion that may reduce the incidence of vertical deviations. METHODS We reviewed consecutive cases of total abducens palsy or esotropic Duane syndrome treated with augmented lateral transposition of the superior and inferior rectus muscles, where the 12 o'clock and 6 o'clock intraoperative positions were initially marked with a dot at the limbus using a surgical pen. The location of the marks was monitored during tying of the augmentation sutures; changes in torsion were monitored intraoperatively. RESULTS Records of 9 cases of augmented vertical rectus transposition were reviewed. On the basis of intraoperative assessment of torsion, by observing the position of preplaced limbal dots, the inferior rectus augmentation suture was tied less tightly than the superior rectus suture, leaving a gap of 1 to 3 mm between the inferior and lateral rectus muscles in 8 of 9 cases. The augmentation suture was totally removed in 1 case. After these intraoperative adjustments, there was no induced intraoperative torsion, whereas further tightening of the inferior suture induced extorsion. Six weeks postoperatively, 8 of 9 patients did not experience a symptomatic vertical deviation. CONCLUSIONS When performing augmented transposition procedures, intraoperative monitoring of torsion may reduce the incidence of inadvertent vertical deviations and torsion. This technique may also be useful in other cases where correction or avoidance of torsion is needed. (J AAPOS 2012;16:136-140)