The purpose of the study at Auckland was to show that in a large study group and with a range of operator experience, the sub-Tenon block (STB) is very effective and has a low potential for sight-threatening complications. The article stated that it was not statistically possible to show that the incidence of ocular injury is lower with a sub-Tenon technique than any other.
With regard to topical versus regional anesthesia, the choice depends on three primary factors: surgeon, patient, and anesthesiologist preferences. Auckland hospital is a teaching hospital with a variable level of expertise for both anesthesiologist and ophthalmologist. Most of the surgeons in our institution have a preference for regional anesthesia for the majority of our patients, because the akinesia and loss of orbicularis tone provides superior operating conditions 1and the best environment to teach junior surgeons. Anesthesiologists prefer regional anesthesia because it is associated with superior intraoperative analgesia. 1–3The patient’s cooperation is more important for topical anesthesia, and many elderly patients have difficulty maintaining a steady eye. Furthermore, there is evidence that the majority of patients prefer regional anesthesia to topical when given the choice. 1
The choice of regional technique will depend on the skill, experience, and personal preference of the operator as well as patient and surgical factors. Although it would be ideal for all anesthesiologists to be experts in all ophthalmic anesthetic techniques, in practice this is not feasible. We have chosen STB as our predominant technique because it provides an excellent degree of analgesia and akinesia, is virtually painless to perform, has a low injectable volume, avoids passage of sharp needles into the orbit, and has an extremely low incidence of significant complications. Performance of the block takes less than 2 min and is well suited to “high-volume” lists. We believe that STB is least likely to result in ocular trauma in the hands of operators with a variable level of expertise. Although it is impossible to be certain that this technique has a lower incidence of complications than other regional techniques, particularly peribulbar anesthesia, there are only a handful of reports of complications from STB in a denominator that can be estimated to be in the hundreds of thousands. Anecdotally, more than 25,000 STB have currently been performed in hospital and “office-based” settings in the Auckland region, with no sight-threatening complications.
I would agree that appropriate training in regional anesthesia of the orbit is a pivotal factor in the safety of any regional technique.