Abstract
Abstract: :
Purpose: To compare the efficacy and efficiency of sub–Tenon's injection versus retrobulbar injection of local anesthetic in vitreoretinal surgery using a prospective, randomized, single–masked clinical trial. Methods:60 patients undergoing vitreoretinal surgery at the Wilmer Eye Institute were randomized to receive either sub–Tenon's injection or retrobulbar injection of 5–ml 50:50 mixture of 2% lidocaine and 0.75% bupivacaine. Three main outcomes were measured: 1. the adequacy of peri–operative pain control was rated by patients in both groups using a quantitative visual analogue scale; 2. the operative surgeon indicated whether he/she perceived patient discomfort during four different stages of the operation: opening of the conjunctiva, vitrectomy (if performed), placement of scleral buckle (if performed), and closing of the conjunctiva; 3. the time needed to achieve local anesthesia and start operative incision was compared between the two groups by reviewing the operative charts. The need for supplemental anesthetic injection, IV sedation, and complications were also monitored. Results: Interim data analysis was performed on the first 24 patients (11 in the sub–Tenon's group and 13 in the retrobulbar group). Based on these data, patients from the sub–Tenon's group reported lower median pain score than patients from the retrobulbar group (1.5 vs 3.0). Percentages of patients with pain as reported by the surgeon were lower for the sub–Tenon’s group than retrobulbar group during opening of the conjunctiva (0% vs 18%), vitrectomy (30% vs 62.5%), and placement of scleral buckle (0% vs 33%), while the reverse was true for closing of the conjunctiva (40% vs 27.3%); however, none of the reported differences were statistically significant. Median pre–incision time was longer in the sub–Tenon’s group than in the retrobulbar group (32 minutes vs 21.5 minutes). There was a tendency for more supplemental anesthesia to be given to retrobulbar patients than to sub–Tenon’s patients. Fewer patients in sub–Tenon's group required IV sedation. Conclusions: Based on analysis of preliminary data, sub–Tenon's injection of anesthetic appears at least as effective as retrobulbar injection in terms of intra–operative pain control. Patients receiving sub–Tenon's injection may require less supplemental anesthesia and IV sedation. However, performing a sub–Tenon's injection may be more time–consuming than performing a retrobulbar injection. Given that this is an on–going clinical study, updated results will be presented at the meeting.
Keywords: vitreoretinal surgery • clinical (human) or epidemiologic studies: outcomes/complications • retina