Regional anaesthesia for cataract surgery: comparison of three techniques.

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Abstract
Two methods of periocular anaesthesia (PI and PII) were compared with the traditional retrobulbar block in a prospective study of 450 patients undergoing elective cataract extraction and intraocular lens implantation. A solution of local anaesthetic containing equal amounts of 2% lignocaine and 0.5% bupivacaine was used in all the groups. Hyaluronidase (75 IU/10 ml of local anaesthetic solution) was added. Three groups of patients were studied, with 150 patients in each group. The retrobulbar injection (group R) was performed with 4 ml of the anaesthetic solution through the lower eyelid inferotemporally and a further 6 ml was injected for seventh cranial nerve block. In the first periocular technique (group PI) the local anaesthetic was injected inferotemporally (5 ml) through the lower lid and superonasally (5 ml) through the upper lid. In the second periocular technique (PII) the injections were performed inferotemporally (5 ml) and into the medial compartment (2 ml) of the orbit at the medial canthus. Satisfactory anaesthesia could be achieved with all of these methods. Additional block because of insufficient akinesia of the muscles was required in 12% (18/150) in group R, in 19% (28/150) in group PI, and in 11% (16/150) in PII. The medial compartment technique (PII) was associated with the highest percentage of total akinesia of the muscles and lowest reblock rate. All three methods produced sufficient analgesia during surgery and there were no differences in the requirements for additional analgesic drugs during surgery. It is concluded that the medial compartment technique represents a good alternative to retrobulbar block.