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 345 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.