Safety and Efficacy of Subtenon Anesthesia in Anterior Segment Surgeries

Abstract

Purpose: The objective of the study was to evaluate the complications of subtenon anesthesia in patients undergoing anterior segment surgeries

Materials and Methods: The study was conducted in the department of ophthalmology, Abbasi Shaheed Hospital, from January 2009 to June 2010. 150 Patients were selected amongst those presenting in outpatient department for anterior segment surgery using non-probability consecutive sampling technique. Patients were scheduled for elective ophthalmic procedures with an expected duration of less than 60 min. Patients with clotting abnormalities, impaired mental status, uncontrolled glaucoma, were excluded from the study. 2 ml of 2% xylocaine with adrenaline (plain xylocaine where adrenaline was contraindicated) was injected using a subtenon cannula in supratemporal quadrant of the eye ball. We recorded complications including patient discomfort, inadequate anesthesia, conjunctival chemosis, subconjunctival haemorrhage, reterobulbar haemorrhage.

Results: A total of 150 patients were operated under subtenon anesthesia. Majority of the procedures performed were extra capsular cataract extraction (55.3%) followed by trabaculectomy (24%). Most common complication in our study was subconjunctival haemorrhage (48%) followed by conjunctival chemosis (37%). Other complications like inadequate anesthesia were seen in 12 (8%) patients and inadequate akinesia in 18 (12%) patients. A second injection was required in 12 (8%) patients. Simultaneous use of topical anesthetic was recorded in 18 (12%) patients. Reterobulbar haemorrhage occurred in a small percentage (2%) of patients in our study. In addition pupillary constriction after delivering the nucleus 45 (30%) patients and positive vitreous pressure leading to raised intra ocular pressure and iris prolapse 3 (2%) patients were also recorded. 58(39%) patients complained of pain and discomfort during the injection.

Conclusion: Majority of complications encountered in this study were minor like subconjunctival heamorrhage, conjunctival chemosis, inadequate anesthesia and akinesia. Major complications like reterobulbar heamorrhage and positive vitreous pressure leading to raised intraocular pressure during the surgery were uncommon but present. Subtenon anesthesia though safe is not devoid of complications.