Comparison of sub-Tenon's anaesthesia by different delivery techniques in cataract surgery

Purpose To compare the analgesic effects of three different delivery techniques of sub-Tenon's anaesthesia in cataract surgery by assessing patients' response to the visceral stimulus. Methods A prospective, randomised study was conducted on 345 eyes of 845 patients undergoing phacoemulsification and posterior chamber intraocular lens implantation. They received anaesthetic infiltration into the sub-Tenon's space through a conjunctival incision (115 eyes), infiltration into the posterior sub-Tenon's space (retrobulbar space) through a conjunctival incision (114 eyes), or injection into the intra-Tenon's space (subconjunctival space) without making a conjunctival incision (116 eyes). Pain scores were recorded when the anterior chamber was irrigated with an acetylcholine chloride solution to achieve miosis after lens implantation. Results There were no significant differences in pain scores among the three groups (chi-squared test of homogeneity p = 0.814). Approximately 10 -20% of patients reported slight to severe: pain at the time of acetylcholine administration. Conclusions The three anaesthetic delivery methods of sub-Tenon's anaesthesia possess similar and reasonable analgesic effects in cataract surgery, but may not block visceral stimuli completely.