Effect of application duration of 2% lidocaine jelly on aqueous lidocaine concentration for topical anesthesia in cataract surgery.
BACKGROUND
To evaluate the intraocular penetration of lidocaine 2% gel after different duration of application and to assess their effects on intraoperative pain.


METHODS
Samples of aqueous humor were obtained in 41 eyes that had phacoemulsification under topical anesthesia with 2% lidocaine gel. The duration between lidocaine gel application and paracentesis was recorded. The aqueous concentration of lidocaine was measured using high performance liquid chromatography (HPLC). Patients were also asked to report the severity of intraoperative pain using a verbal analogue scale. Correlation analysis was performed to analyze the relationship between duration of lidocaine gel application, aqueous lidocaine concentration and intraoperative pain score.


RESULTS
The mean duration of lidocaine gel application was 20.3+/-6.1 min and the mean aqueous lidocaine level was 14.2+/-8.5 micro g/ml. Longer duration of lidocaine gel application was significantly associated with higher aqueous concentration of lidocaine (Spearman's rho=0.58, P<0.001). Eyes in which lidocaine gel was applied for 20 minutes or more had significantly higher aqueous lidocaine level (two-tailed t-test, P=0.001) However, the duration of lidocaine gel application and the aqueous concentration of lidocaine showed no correlation with the patent's perceived pain score (P=0.20 and P=0.79, respectively).


CONCLUSIONS
Increase in duration of lidocaine gel application resulted in higher aqueous concentration of lidocaine. Patients' level of perceived pain during phacoemulsification under lidocaine gel anesthesia was not related to the intraocular lidocaine absorption level after 10 min of gel application.
Department of Ophthalmology, Hong Kong Sanatorium and Hospital, Hong Kong, SAR, People's Republic of China.
Alvin K H
AK
Kwok
Timothy Y Y
TY
Lai
Vincent Y W
VY
Lee
Yat-Shan
YS
Yeung
Kai-On
KO
Chu
Calvin C P
CC
Pang
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000772:Anesthesia, Local / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001082:Aqueous Humor / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005782:Gels; D006801:Humans; D019654:Lens Implantation, Intraocular; D008012:Lidocaine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis; D010147:Pain Measurement; D010149:Postoperative Pain; D018918:Phacoemulsification
D000779:Anesthetics, Local; D005782:Gels; D008012:Lidocaine