Aqueous humor levels of topically applied bupivacaine 0.75% in cataract surgery

PURPOSE: To measure the intraocular levels of bupivacaine 0.75% topically applied before phacoemulsification and to develop standards for topical anesthesia in cataract surgery. SETTING: Department of Ophthalmology, University Hospitals of Leicester, Leicester, United Kingdom. METHODS: Forty eyes having phacoemulsification for senile cataract under topical anesthesia without sedation were randomly assigned to 1 of 2 preoperative topical anesthesia regimens. Bupivacaine 0.75% was applied in 0.1 mL drops 3 times in the 30 minutes before surgery in 18 eyes and 6 times in the 60 minutes before surgery in 22 eyes. Aqueous humor and serum samples were taken at the start of surgery and the bupivacaine levels measured. A visual analog pain score scale was used to indicate intraoperative pain. RESULTS: The mean aqueous humor level of bupivacaine was 5.9 microg/mL +/- 4.3 (SD) after 3 drops and 5.7 +/- 4.0 microg /mL after 6 drops. The blood levels were less than 1.0 microg/mL. There was no statistically significant difference in the intraocular level of bupivacaine between the 2 groups. There was no difference in the age or sex distribution between the 2 groups, although there was an increase in the intraocular level of bupivacaine with age (approximately 1.4 microg/mL per decade; P =.048). There was no clear pattern associating the pain score with age, sex, or intraocular level of bupivacaine. CONCLUSIONS: A 3-drop regimen of bupivacaine 0.75% in the half hour before cataract surgery penetrated the eye as effectively as 6 drops in the 1 hour before surgery and provided good analgesia for phacoemulsification. Bupivacaine 0.75% penetrated the eye increasingly effectively with increasing age.