Onset of Analgesia and Ocular Akinesia Following Posterior Sub-Tenon's Anesthesia With 2% Lignocaine Using a Blunt Cannula

BackgroundPosterior sub-Tenon's anesthesia is widely used for ophthalmic surgery because it can provide effective analgesia and ocular akinesia while avoiding a sharp needle within the orbit.This study evaluated the onset of complete analgesia and ocular akinesia after posterior sub-Tenon's administration of 2% lignocaine through a blunt cannula and documented associated complications. MethodsThis retrospective single-arm observational study included 50 eyes of 50 adult patients who underwent elective ophthalmic surgery at Birat Rani Eye Hospital, Biratnagar, Nepal.Patients aged 18 years or older who underwent elective ophthalmic surgery under posterior sub-Tenon's anesthesia during the study period (3rd of February 2025 to 28th of April 2025) were eligible for inclusion.Patients were identified retrospectively from hospital medical records and included consecutively if they had complete documentation of the posterior sub-Tenon's anesthesia procedure and the relevant postoperative clinical assessments.Following topical anesthesia and aseptic preparation, 4 mL of 2% lignocaine was administered into the posterior sub-Tenon's space through a blunt cannula.The time from completion of injection to complete analgesia and complete ocular akinesia was recorded as per hospital protocol.Block-related complications were documented during the peri-operative period. ResultsOf the 50 participants, 29 (58%) were female, and 21 (42%) were male.The mean time to complete analgesia was 189.24 seconds (three minutes nine seconds), ranging from 150 to 248 seconds.The mean time to complete ocular akinesia was 224.96 seconds (three minutes 45 seconds), ranging from 180 to 280 seconds.Chemosis occurred in 12 eyes (24%) and subconjunctival hemorrhage in seven eyes (14%).No cases of globe perforation, retrobulbar hemorrhage, optic nerve injury, extraocular muscle damage, vasovagal attack, inadvertent subarachnoid anesthesia, or globe ischemia were observed. ConclusionPosterior sub-Tenon's anesthesia using 4 mL of 2% lignocaine administered through a blunt cannula provided rapid onset of analgesia and ocular akinesia in this series.The observed complications were predominantly minor, and no serious anesthesia-related complication was recorded.Larger comparative studies are required to establish the effectiveness and safety of this technique relative to other ophthalmic anesthetic approaches.