Don't forget the heart when looking at the risk of postoperative pulmonary complications.

we are convinced that sub-Tenon blocks produce a more consistent (reproducible) anesthesia than do peribulbar injections. This probably is due to anatomic reasons explained in our previous articles. –7 From an anatomic point of view, the difference between both technique groups can be better understood by using an analogy with perimedullary blocks: peribulbar injection can be assimilated to epidural injection, whereas sub-Tenon block corresponds to spinal injection.