Risk of torsion in superior rectus transposition surgery augmented with posterior scleral fixation sutures

It has been reported that superior rectus transposition combined with medial rectus recession can provide as good results as transposition of both vertical rectus muscles, with no adverse effects on torsion or postoperative vertical misalignment. Further augmentation of transposition surgery can be achieved through the use of posterior fixation sutures, myopexy and botulinum toxin into the medial rectus. We report a patient with complete bilateral traumatic sixth cranial nerve palsies who underwent sequential superior rectus transposition surgery combined with medial rectus recession. The surgery was augmented with a myopexy (posterior suture joining superior and lateral recti with no scleral fixation) in the first eye and with a posterior fixation suture (with scleral fixation) in the second eye. After the second procedure, despite a significant improvement in horizontal alignment, the patient developed 15 degrees of incyclotorsion which was attributed to the scleral fixation suture. The patient underwent removal of the scleral suture and 3 months postoperatively had a significant reduction in incyclotorsion to 8 degrees; however this continued to be a barrier to fusion. Vertical rectus transposition of superior and inferior recti augmented with posterior scleral fixation sutures is one type of conventional surgery for complete lateral rectus palsy. In more recent times, it has become common to transpose the superior rectus alone along with recession of the contracted medial rectus. This procedure can also be augmented with a posterior fixation suture which may or may not be attached to the sclera. Whilst this surgery has gained popularity it is not without risk as demonstrated by our case in which transposition of the superior rectus was associated with postoperative incyclotorsion. In this case a possible explanation may be the use of a the posterior scleral fixation suture as it did not occur when no scleral fixation was used. Furthermore, removal of the posterior scleral fixation suture did reduce the torsion significantly although it did not eliminate it.