PROSPECTIVE-STUDY OF SUB-TENONS VERSUS RETROBULBAR ANESTHESIA FOR INPATIENT AND DAY-SURGERY TRABECULECTOMY

Purpose: Several retrospective studies have demonstrated the safety an d efficacy of sub-Tenon's anesthesia in ocular surgery. This is the fi rst prospective randomized study comparing sub-Tenon's versus retrobul bar anesthesia for glaucoma surgery. Methods: Thirty-nine patients und ergoing both inpatient and day surgery trabeculectomy were randomized to receive retrobulbar or sub-Tenon's anesthesia. Retrobulbar anesthes ia consisted of a 1.5-ml injection of a 1:1 mixture of 2% lidocaine wi thout epinephrine and 0.5% plain bupivacaine with hyaluronidase. Sub-T enon's anesthesia consisted of 2% lidocaine without epinephrine inject ed over the superior, medial and lateral recti muscles. Both groups re ceived a van Lint lid block and a standardized sedative. Outcome param eters evaluated included patient demographics, operative complications , intraoperative and postoperative patient comfort, and volume of anes thetic. Results: Seventeen patients were randomized to the retrobulbar group and 22 to the sub-Tenon's group. Patient discomfort was statist ically similar between the groups. There was no statistical difference between groups with respect to quantity of sedative received, surgica l exposure, eye movements, or operative complications- A retrobulbar h emorrhage, however, developed at the time of retrobulbar anesthesia in one patient, requiring cancellation of surgery. A larger volume of lo cal anesthetic was required in the retrobulbar group versus the sub-Te non's group (1.8 versus 1.1 ml; P < 0.01). Patients receiving retrobul bar injections were more likely to require additional anesthesia (P < 0.01) and postoperative analgesics (P < 0.05) compared with patients u ndergoing sub-Tenon's injection. There was no significant difference b etween the groups with respect to age, sex, or operated eye. Conclusio ns: Sub-Tenon's anesthesia is safe and effective for patients undergoi ng either inpatient or day-surgery trabeculectomies, and it requires l ess local anesthetic than retrobulbar anesthesia.