Effectiveness of Subconjunctival 0.5% Bupivacaine for Postoperative Analgesia after Intravitreal Silicon Oil Removal Surgery

BACKGROUND: Intravitreal silicon oil removal surgery can cause mild-to-moderate postoperative pain and discomfort in most patients. Postoperative pain can be managed by using many methods, including a local anesthetic drug. One of the common local anesthetic drugs is 0.5% bupivacaine. The application techniques also vary, such as subconjunctival application. It was a good alternative for postoperative analgesia in the ophthalmic surgery because of its minimal risks and complications. The purpose of this research was to measure the effectiveness of subconjunctival 0.5% bupivacaine for postoperative analgesia in silicon oil removal surgery. METHOD: This was a double-blind randomized clinical study in patients undergoing elective intravitreal silicon oil removal surgery at Cipto Mangunkusumo Hospital. Thirty consecutive patients, enrolled from October 2016 to February 2017, were randomized to receive subconjunctival 0.5% bupivacaine or subconjunctival placebo (0.9% NaCl) at the end of the surgery. The primary outcome was the pain score 24 hours after surgery, using a 100 mm Visual Analogue Scale (VAS). Intravenous injection of tramadol 50 mg was given if the VAS >4. Secondary outcomes were the time to first analgesic requirement and the incidence of nausea/vomiting. Statistical analysis was conducted to measure the difference between 24 h pain score in the bupivacaine group (B) and that in the placebo group (NS). RESULT: The overall 24 hours' postoperative pain score was significantly different between the bupivacaine group and the placebo group (p=0.001). In the 24 hours after surgery, there were only five patients needing additional analgesia in the placebo group. The time to first analgesic requirement was significantly different between the two groups (p=0.042). Nausea/vomiting only happened in the placebo group with proportions 6% and 3%, respectively. CONCLUSION: Subconjunctival 0.5% bupivacaine was effective for postoperative analgesia in intravitreal silicon oil removal surgery.