Peribulbar anaesthesia and needle length.

This retrospective audit of 87 consecutive patients undergoing routine cataract surgery compared the effect of peribulbar local anaesthesia using 16 mm and 25 mm, 25 gauge needles to administer the anaesthetic. The effect on optic nerve function was observed. There was a significant increase of complete amaurosis in the group where the 16 mm needle had been used. This may be explained by more effective anatomic placement of the 16 mm needle within the orbit, allowing access to the retrobulbar space via fascial septae. There was significantly more lid akinesia with the 16 mm needle. None of this group required an additional facial nerve block, as opposed to 14% of the 25 mm needle group. The use of a 16 mm needle is theoretically safer than a 25 mm needle to administer a peribulbar anaesthetic, in this review it was also demonstrated to be more effective.