Abstract
Abstract: :
Purpose: To determine whether the single medial canthus episcleral (sub-Tenon's) injection for local anesthesia is a safe and effective choice for posterior segment surgery (PSS) Method: Seventeen patients prospectively underwent sub-Tenon's local anesthesia for vitreoretinal surgery (n = 52) or scleral buckling and cryotherapy procedures (n = 18). Mean duration of surgery was 80 mn (range 30 to 180 mn). All patients received a single medial canthus sub-Tenon's injection through a 25 gauge short bevel needle containing a mixture in equal parts of 0.5% bupivacaine and 2.0% lidocaine with 25 IU/ml hyaluronidase , without any incision of the conjunctiva or the Tenon's capsule.The injected volume was not predetermined but adjusted to each patient. The mean injected volume was 10 ml (range 6 to 12 ml). Motor blockade (akinesia) was referred as the main index of anesthesia effectiveness. The proportion of cases receiving a supplementation : intravenous anesthesia preoperatively or intraoperatively, or additional local anesthesia was counted. The satisfaction of the patient, surgeon and anesthesiologist have been evaluated. Complications with episcleral anesthesia have been monitored. Results: Episcleral (sub-Tenon's) anesthesia provided a quick onset of anesthesia, good akinesia and high rate of complete blockade. Fifteen patients received additional anesthesia : six received additional preoperative sub-Tenon's anesthesia (supplemental injection was performed using the same mixture at the same site), one received intraoperative local anesthesia, eight received intravenous anesthesia. Supplementation was required for lasting surgery (≷ 2 hours) or painful procedures (posterior scleral buckling or cryotherapy). The satisfaction scores were very good in 66 cases. No associated ocular or systemic complications were observed. Conclusion: Medial canthus episcleral (sub-Tenon's) single injection for local anesthesia is a suitable alternative for PSS. It is relatively safe and effective for achieving local anesthesia during vitreoretinal surgery or scleral buckling and cryotherapy procedures lasting less than 3 hours.