Surgery with intraoperative botulinum toxin-A injection for the treatment of large-angle horizontal strabismus: a pilot study

Some patients with large-angle strabismus may refuse or may not meet the criteria for binocular surgical correction. A second option for these patients involves a monocular procedure, which can be performed under peribulbar anesthesia and offers certain advantages (1). Improved surgical outcomes for conventional procedures may enhance the effectiveness of monocular surgery. In theory, this enhancement could be achieved by the coadjuvant use of intraoperative botulinum toxin A (BT) (2). To date, few reports have described the intraoperative injection of BT (3-5). Owens et al. (3) performed supramaximal monocular recession-resection surgeries and successfully used intraoperative BT in three large-angle exotropia patients. Khan (4) successfully performed two-muscle horizontal rectus surgery with simultaneous BT injection in patients with severe large-angle esotropia. Additionally, seven patients underwent bilateral medial rectus recession and bilateral BT injection, and one patient underwent a unilateral recess/ resection surgery with medial rectus BT injection. These results indicated that bilateral medial rectus recession with simultaneous BT injection is a safe and effective surgical procedure for patients with severe large-angle esotropia, although more extensive studies are required to confirm these findings. Öskan et al. (5) reported the results of 10 patients with large-angle horizontal deviations (esoor exotropia) who received BT injections into one recessed muscle and concluded that such treatment may provide greater surgical success compared to conventional horizontal rectus muscle surgeries. The results of these uncontrolled studies have reinforced the hypothesis that long-term realignment of the eyes can be achieved with surgery plus BT administration. However, the effectiveness of the addition of intraoperative BT compared to surgery alone is unclear. In this pilot study, we used a prospective, controlled, and randomized double-blind methodology to examine the effectiveness of BT injection in combination with surgical treatment compared to surgical treatment alone for the correction of large-angle horizontal deviations under local anesthesia.