Lidocaine diffusion after intracameral injection

Purpose:To determine the lidocaine diffusion space, we compared lidocaine a quous humor concentration in topical anesthesia with 1 % lidocaine intracam eral injection and in peribulbar anesthesia with 2 % lidocaine prior phacoe mulsification. Material and method: A gas chromatography technique of analyzing 100 mu l a queous humor was used to detect the presence of lidocaine prior to phakoemu lsification cataract surgery in two groups of patients : - group A : after peribulbar anesthesia with 10 mi 2 % lidocaine, - group B: after 1 % tetracaine topical anesthesia and 0.5 mi intracameral injection of 1 % preservative-free lidocaine. The intracameral volume was estimated mathematically in group B. Endothelia l cells loss was analyzed in two groups with non contact specular microscop y. Results: Lidocaine was detected in aqueous humor with a good reliability. T he mean concentration after intracameral injection was 6 330 mu g/ml and wa s higher than after peribulbar injection. This concentration was near than theorical intracameral rate, suggesting that there was no diffusion in the posterior segment. There was no significant difference in the 2 groups in e ndothelial cells loss. Conclusion: Intracameral injection of lidocaine is an effective technique t o anesthetize intracameral structures without diffusion in posterior segmen t prior to phakoemulsification.