Prilocaine 3% is superior to a mixture of bupivacaine and lignocaine for peribulbar anaesthesia

We have compared motor block of the extraocular muscles produced by injections of 3% prilocaine and a mixture of equal parts of 2% lignocaine and 0.75% bupivacaine into the medial compartment of the orbit. A volume of 8 ml was used initially, and a vasoconstrictor and hyaluronidase were added to both solutions. Ninety patients undergoing cataract surgery were allocated randomly to one of two groups in double-blind study. Eight minutes after block insertion, the median ocular movement score in the prilocaine group was 1 and in the lignocaine-bupivacaine group 3. This difference was statistically significant (P = 0.016). Twenty of the patients who received prilocaine and 29 of the patients who received the lignocaine-bupivacaine mixture required an additional inferotemporal injection. This difference was not statistically significant (P = 0.094).