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

Abstract

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 μg/mL ± 4.3 (SD) after 3 drops and 5.7 ± 4.0 μg /mL after 6 drops. The blood levels were less than 1.0 μg/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 μg/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.