THE EFFECTS OF LIDOCAINE AND BUPIVACAINE ON THE RABBIT RETINA

The toxic action of two commercial anesthetics, lidocaine and bupivaca ine, on the functional and morphologic integrity of the retina was inv estigated in albino and pigmented rabbits. The experimental drug was i njected into the vitreous of one eye, while saline solution was inject ed into the fellow eye. Retinal function was assessed from the electro retinogram and the visual evoked potential. Retinal structure was exam ined at the light microscopic level. Ten milligrams of lidocaine did n ot affect the electroretinogram and the visual evoked potential respon ses, though structural damage could be detected close to the site of i njection. A lower dose of 5 mg did not produce any detectable physiolo gic 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 microscop y. The results of this study demonstrate that lidocaine and bupivacain e are nontoxic to the rabbit retina at concentrations that are effecti ve for retrobulbar anesthesia.