Postoperative Analgesic Efficacy of Sub-Tenon's Block with Levobupivacaine in Retinal Surgery under General Anesthesia

BACKGROUND: Vitreoretinal surgery is associated with undesirable intraoperative and postoperative complications including pain, postoperative nausea and vomiting, and oculocardiac reflex (OCR). Systemic analgesics have side effects and are contraindicated in some cases. We hypothesized that the preoperative sub-Tenon's injection of levobupivacaine with general anesthesia would decrease postoperative pain and intraocular pressure as well as the incidence of complication. METHODS: Eighty patients who were presented for vitreoretinal surgery, aged 30–60 years, were enrolled in the study. General anesthesia was administrated to all patients; then, they were randomized into two equal groups (40 each) – Group I: patients received 5 mL placebo solution for sub-Tenon's block and Group II: patients received 4 mL levobupivacaine 0.5% in 1 mL saline for sub-Tenon's block. Postoperative pain was evaluated using a verbal pain scale. Surgeon satisfaction, postoperative analgesic consumption, and perioperative hemodynamics were also reported. RESULTS: Verbal rating pain scores were significantly lower at the first 6 h postoperative in Group II (sub-Tenon's levobupivacaine) compared to Group I (sub-Tenon's placebo). First analgesic rescue time and total dose of analgesic consumption were significantly reduced in Group II compared to Group I. There was a lower incidence of OCR with sub-Tenon's levobupivacaine (Group II), also surgeon satisfaction was significantly superior in the same group. CONCLUSION: The combination of general anesthesia with sub-Tenon's block using levobupivacaine in retinal surgery patients reduces pain scores after surgery; total analgesia requirement also decreases the incidence of OCR.