Effect of intracameral injection of lidocaine and carbachol on the rabbit corneal endothelium.

Purpose: To determine the effect of intracameral injection of preservative-free lidocaine 1% and carbachol 0.01% on corneal endothelial cells of rabbits.

Setting: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.

Methods: Forty eyes of 20 New Zealand White rabbits were divided into 2 equal groups. In the first group, 1 eye was injected with 0.02 mL of preservative-free lidocaine 1% and the fellow eye was injected with 0.02 mL of normal saline as a control. In the second group, 1 eye was injected with 0.02 mL of carbachol 0.01% and the fellow eye was injected with 0.02 mL of normal saline. Specular microscopy was used to evaluate corneal endothelial cell loss and corneal thickness 1 week and 1 month postinjection. For morphologic studies, corneal buttons were excised and stained with alizarin red with trypan blue. Scanning electron microscopy (SEM) examination was performed.

Results: Specular microscopy revealed no significant endothelial cell loss and normal endothelial thickness with the intracameral injection of preservative-free lidocaine 1% and carbachol 0.01% compared with the control eye. Alizarin red with trypan blue stain and SEM examinations revealed smooth, distinct, and intact intercellular borders and normal viability of corneal endothelial cells in both groups.

Conclusions: Intracameral injections of preservative-free lidocaine 1% and carbachol 0.01% do not produce morphologic and functional changes in the corneal endothelial cells of rabbits.