Efficacy of the Subtenon Block in Children Undergoing Strabismus Surgery: A Systematic Review and Meta-Analysis.

Purpose: To investigate the efficacy of the subtenon block in preventing postoperative complications in children undergoing strabismus surgery.

Design: Systematic review and meta-analysis.

Methods: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Scopus, Web of Science, and clinicaltrials.gov. All randomized controlled trials investigating the efficacy of the subtenon block in children undergoing strabismus surgery were included. Outcomes included severity of pain after surgery, number of children requiring postoperative opioid and nonopioid analgesia, and the incidences of postoperative nausea and vomiting, oculocardiac events, and block-related complications. We pooled continuous outcomes using a random-effects model to calculate the mean difference (MD) and/or standardized MD and corresponding 95% confidence intervals (CI). Dichotomous outcomes were pooled using a random-effect model to calculate the relative risk (RR) and corresponding 95% CI. Risk of bias was assessed using the Cochrane Risk of Bias instrument and quality of evidence was assessed using a Grading of Recommendations Assessment, Development, and Evaluation approach.

Results: Nine randomized controlled trials (607 participants) were included. We found evidence for an effect of the subtenon block in reducing pain at 20 to 40 minutes after surgery (MD -1.9, 95% CI -2.2 to -1.5; high-quality evidence) and on admission to PACU (MD -1.8, 95% CI -2.2 to -1.4; moderate-quality evidence); however, there was no difference in pain scores at 6 hours after surgery. In addition, evidence was found that the subtenon block decreased the number of children requiring postoperative opioid (RR 0.59, 95% CI 0.37-0.92; high-quality evidence) and nonopioid (RR 0.52, 95% CI 0.27-0.98; moderate-quality evidence) analgesia, and the incidences of postoperative vomiting (RR 0.31, 95% CI 0.12-0.7; high-quality evidence) and intraoperative oculocardiac events (RR 0.40, 95% CI 0.26-0.60; high-quality evidence). Other secondary outcomes had low or moderate-quality evidence. Risk of bias was low in six trials and high in three. There were no reports of block-related complications.

Conclusions: Our findings suggest that the subtenon block reduces the severity of early postoperative pain and the incidences of postoperative vomiting and intraoperative oculocardiac events compared with controls in children undergoing strabismus surgery.

Review Registration: PROSPERO (CRD42015025443).