Purpose: To compare the analgesic effects of different doses of sub-Tenon's anesthesia in cataract surgery by assessing patient response to visceral stimulus.
Setting: Inouye Eye Hospital, Tokyo, Japan.
Methods: A prospective study was done of 1019 eyes of 1019 patients having phacoemulsification and posterior chamber intraocular lens implantation. They received a 1.0 mL (391 eyes), 2.0 mL (366 eyes), or 3.0 mL (262 eyes) anesthetic infiltration into the sub-Tenon's space. Pain scores were recorded when the anterior chamber was irrigated with an acetylcholine chloride solution to attain miosis after lens implantation.
Results: The distribution of pain scores was significantly different among the 3 groups (P < .0001, Kruskal-Wallis test). Multiple comparison revealed that the 3.0 mL anesthetic infiltration offered significantly higher analgesic effects than the 2 lower doses. The 3.0 mL sub-Tenon's anesthesia effectively blocked the visceral stimulus.
Conclusion: For cataract surgery, 3 mL is the optimal dose of anesthetic solution in sub-Tenon's anesthesia.