The Effects of Bupivacaine and Lidocaine on the Corneal Endothelium when Applied into the Anterior Chamber at the Concentrations Supplied Commercially

Abstract

Purpose: To investigate the direct toxic effects of bupivacaine HCl 0.5% and lidocaine HCl 2%, two commonly used injectable local anesthetic agents, on the corneal endothelium when applied intracamerally. Methods: Two groups were formed, each consisting of 12 pigmented rabbits, and 0.2 ml of the anesthetic agent were injected intracamerally into the right eyes. The central corneal thicknesses and corneal clarities were evaluated preoperatively and at 3, 6, 9, 12 h and 1, 3, 7 days postoperatively. While the central corneal thicknesses were evaluated by ultrasonic pachymetry, the corneal opacification scored between 0 and 3 was assessed by biomicroscopic examination and photographs. Results: Both bupivacaine and lidocaine caused corneal thickening in the 3- to 12-hour measurements. In addition, there was significant corneal opacification in both groups in the 3-hour and 3-day measurements. The corneal thickening and corneal opacification determined during 3- and 6-hour measurements in the eyes which received intracameral bupivacaine were significantly higher than those determined in the lidocaine-injected group. In both groups, the corneal thickness and corneal clarity scores returned to the preoperative values on the 1st and 7th days, respectively. Conclusions: When applied into the anterior chamber at the concentrations supplied commercially, both bupivacaine and lidocaine cause statistically significant corneal thickening and clinically significant corneal opacification. It should be noted that the injection of these agents into the anterior chamber during the operation at the concentrations supplied commercially may be a potential risk factor for endothelial injury.