The effects of lidocaine and bupivacaine on the rabbit retina.

The toxic action of two commercial anesthetics, lidocaine and bupivacaine, on the functional and morphologic integrity of the retina was investigated in albino and pigmented rabbits. The experimental drug was injected into the vitreous of one eye, while saline solution was injected into the fellow eye. Retinal function was assessed from the electroretinogram and the visual evoked potential. Retinal structure was examined at the light microscopic level. Ten milligrams of lidocaine did not affect the electroretinogram and the visual evoked potential responses, though structural damage could be detected close to the site of injection. A lower dose of 5 mg did not produce any detectable physiologic or morphologic damage. The only dose of bupivacaine used, 0.5 mg, was not toxic to the albino and pigmented rabbit retinas, as assessed by the electroretinogram, visual evoked potential, and light microscopy. The results of this study demonstrate that lidocaine and bupivacaine are nontoxic to the rabbit retina at concentrations that are effective for retrobulbar anesthesia.