Subtenons lidocaine injection for postoperative pain relief after strabismus surgery in children: A prospective randomized controlled trial

Background. We previously reported a pilot study of the use of subtenons lidocaine after primary, unilateral strabismus surgery in children. This study suggested an association between subtenons lidocaine administration at the conclusion of surgery and a reduction of pain in the immediate postoperative period. As a result of this pilot study we performed a full-scale prospective, randomized controlled trial to fully evaluate the efficacy of this intervention. Methods: Children undergoing primary surgery or reoperations for strabismus were recruited. If randomized to the treatment group, 1 ml of 2% lidocaine was injected into the subtenons space of each operated eye, just prior to conjunctival closure. The child's parents, who were masked to the intervention, assessed pain over 4 h postoperatively using an objective pain-scoring tool. Pain scores were recorded on return to the ward (0 h, approximately 20 to 30 min after the completion of surgery) and at 1, 2, and 4 h later. Results: One hundred eleven children were recruited, of whom 91 (82.0%) underwent unilateral and 20 (18.0%) underwent bilateral surgery. Ninety operations (81.1%) were primary procedures and 21 (18.9%) were reoperations. Fifty-four children (48.6%) were randomized to the treatment group and 57 (51.4%) were randomized to the control group. A subtenons lidocaine injection was associated with a significant reduction in pain at the 0 h observation (P = 0.0056), and the total pain score over the 4-h postoperative period was significantly lower in the treatment group compared to controls (P = 0.0381). There was no difference between the groups with respect to the need for additional systemic analgesia (P = 0.307). Conclusion: This study showed that an intraoperative injection of subtenons lidocaine is associated with a significant reduction in postoperative pain during the first postoperative hour for all types of childhood strabismus surgery. There was no difference between the groups in the need for systemic analgesia.