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Editor,—We read with great interest the observations of Chen et al 1on the occurrence of inadvertent injury to the globe secondary to peribulbar anaesthesia. We found it particularly relevant because we have recently encountered similar cases, but without serious consequences.
The incidence of globe perforation following periocular anaesthesia is probably much more than the previously believed 0.1%2-4and more cases would be identified with a high index of suspicion and postoperative fundal examination through a dilated pupil. At the time of injection it is more likely for the needle to travel through the globe (seen as an entry and exit wound) and as a result the anaesthetic is still injected in the periocular space, leading to adequate anaesthesia and akinesia. Peribulbar anaesthesia, which was reported as a safer alternative to the retrobulbar injection5 6 was implicated in all our cases and might not be as safe as was previously believed.
It is easy to point a finger at the person administering the block and attribute the condition to the learning curve especially of the trainee; however, we feel that a few steps might be useful. The risks of ocular perforation may decrease with use of the long 25 gauge (25 mm) needle instead of the longer (37.5 mm) retrobulbar needle. The use of blunt needles has been recommended to prevent injury to the globe.7 Perforation is more likely in eyes with an axial length greater than 26 mm6 it is a safer option to administer the local anaesthetic in the sub-Tenon’s space. We have found it particularly easier to stay away from the globe by going transconjunctivally rather than through the skin. Also it is always suggested that before injecting the needle is moved sideways to ensure that it has not engaged the eyeball. This not only warns us of the possibility of the needle being in the globe but also prevents any injection of anaesthetic in the globe. However, one should not underestimate the importance of adequate training of personnel and suspicion in the immediate postoperative period. But there is always going to be the occasional “uncooperative patient”8—a situation where the utmost caution has to be exercised.
Editor,—We are delighted for the opportunity to reply to the comments of Nambiar and Rassam regarding our recent small case series of inadvertent injury to the globe secondary to peribulbar anaesthesia. While the incidence of inadvertent injury to the globe during peribulbar anaesthesia was as low as 0.006% in a paper by Davis and Mandel, the variety of reported incidences may be due to variations in definitions and techniques of peribulbar anaesthesia. We tried to emphasise in our report that the experience of the administrator with peribulbar anaesthesia is not as important as others would suggest as demonstrated by the fact that three of the inadvertent injuries were caused by experienced consultants (an anaesthetist and an ophthalmologist).However, we do feel that early recognition of an inadvertent injury and its early assessment by a vitreoretinal specialist is of the utmost importance, a fact highlighted by other authors.
From the viewpoint of injection technique, blunt needles do not prevent inadvertent injury to the globe. Furthermore, the length of the needle used by individuals varies and the report by Davis and Mandel described a posterior peribulbar technique using a long 37.5 mm retrobulbar needle. We, however, prefer to use a shorter 32 mm 25 gauge needle to reduce the likelihood that the needle will go close to the equator of the globe. We agree that asking the patient to look from side to side may be useful in confirming that the needle is in the correct position but whether the injection should be transcutaneously or transconjunctivally is a matter of personal preference. Finally, we disagree that an axial length of 26.0 mm or more is in itself an indication to use another form of anaesthesia. However, each patient and their possible risk factors should be assessed individually before a decision regarding appropriate anaesthesia for any ophthalmic procedure. It is at this point that the administrator’s training and experience are essential in reducing any potential complications.