Comparison of catecholamine and pressor effects in peribulbar and retrobulbar anaesthesia in cataract surgery

Peribulbar anaesthesia is now established as an alternative to retrobulbar anaesthesia for cataract surgery. However, the larger volume of anaesthetic solution in the extraconal orbit with the peribulbar technique might carry a higher risk of systemic side-effects. To assess this risk we carried out a prospective randomised comparison of plasma catecholamine and pressor effects between the two methods of anaesthesia in 40 patients. Plasma adrenaline and noradrenaline, heart rate, blood pressure, pain and anxiety were documented before and after local anaesthesia and during surgery. There were no statistically significant differences between the responses of the two groups. Both groups demonstrated a statistically significant rise in plasma adrenaline and heart rate. However, this change was minimal compared with the effects reported after severe stress or general anaesthesia, emphasising the importance of allaying patient anxiety during local anaesthesia. We have therefore shown that the larger volume of extraconal orbital anaesthetic solution with the peribulbar technique produces no greater risk of systemic pressor effects.