Background: To investigate the biochemical changes on the oxidant/antioxidant balance in corneal and lens tissues in rabbits, and to determine the relative corneal endothelial toxicities following the injection of intracameral anaesthetic agents: levobupivacaine 0.5% or lidocaine 2%.
Methods: The experiment was conducted using New Zealand rabbits. The rabbits were randomly divided into three experimental groups. Twenty eyes received injections of 0.2 ml of one of the two anaesthetic preparations and ten control eyes received injections of 0.2 ml of balanced salt solution. Corneal thickness and clarity were measured before and 3 and 6 hours after surgery. Anterior chamber reaction was evaluated 1, 3, and 6 hours after the surgery. In corneal and lens tissues, malondialdehyde (MDA) and total thiol (SH) levels were measured with spectrophotometric methods.
Results: Levobupivacaine 0.5% caused corneal thickening, oedema, and anterior chamber reaction (p < 0.001). There were no biochemical changes in the levobupivacaine group (p > 0.05). We observed no change in the corneal thickness, oedema, and anterior chamber reactions while the level of MDA significantly increased in corneal and lens tissues (p < 0.001, p = 0.015, respectively), and the level of SH significantly decreased in the lens tissue in the lidocaine 2% group (p < 0.001).
Conclusions: The results of this study suggest that levobupivacaine 0.5% is shown to have an immediate toxicity on corneal endothelium. Lidocaine 2% causes oxidative damage on corneal and lens tissues. Surgeons should not prefer repetitive and high doses of intracameral lidocaine and use it in the presence of corneal pathology during cataract surgery.