Retrobulbar anesthesia and orbicularis akinesia.
After noting that simple retrobulbar injection often caused orbicularis akinesia, we evaluated this phenomenon prospectively. A total of 50 patients were given a standard injection using 3 cc of a 50-50 mixture of 0.75% bupivacaine and 2% lidocaine with epinephrine and hyaluronidase. The entire 3 cc was injected into the muscle cone through an inferolateral lid entry using a 35-mm retrobulbar needle of either 23- or 27-gauge. Injection was considered successful if orbicularis function was sufficiently reduced to proceed with an intraocular case after a single retrobulbar injection. If facial nerve block was necessary or if the patient's lid moved during surgery, then the procedure was considered a failure. Of the 50 patients, 44 achieved adequate akinesia of the orbicularis after retrobulbar injection alone, giving a success rate of 88%. Benefits of this method include lower drug volume. decreased chance for direct nerve damage during a facial nerve block, less pain, less ecchymosis, and less edema following surgery.