Ophthalmic regional anesthesia: medial canthus episcleral (sub-tenon) single injection block.

BACKGROUND The purpose of this study was to evaluate the efficacy and safety of episcleral single-injection anesthesia in a large number of patients. METHODS Over a period of 5 yr, in four institutions, anesthesiologists involved in this prospective study completed a standardized form to evaluate single-injection medial canthus high-volume episcleral anesthesia. The success rate of the block was rated according to an akinesia score. The study parameters included demographic data, surgical procedure, and anesthetic management. All patients were followed up at least until postoperative day 1, and all complications, pain, and discomfort were noted. Statistical analysis was done to assess the risk factors for complications. RESULTS A total of 2,031 patients were included in the study. The most frequent surgical procedures performed were phacoemulsification and posterior chamber artificial lens implantation (91.0%). A total of 66 complications (3.3%) occurred in 60 patients. One patient had a retrobulbar hemorrhage, and 59 had one or two more minor incidents or pain/discomfort with the procedure. The complications consisted of subconjunctival hematoma (1.3%), ocular hypertonia (0.4%), and chemosis (0.30%). Statistical analysis revealed that inexperience in the technique represented a risk factor for complications. CONCLUSIONS This is the first survey of a large experience in episcleral single-injection anesthesia, a form of anesthesia that does not preclude sharp-needle complications and does require training. Only one complication occurred among 2,031 patients; however, a larger number of patients is needed to definitively evaluate the safety of episcleral single-injection anesthesia.