Sub-Tenon's versus peribulbar anaesthesia for cataract surgery

We present a comparison of one quadrant sub-Tenon's anaesthesia and peribulbar anaesthesia. Patient discomfort during injection of anaesthetic and during cataract surgery was assessed using a 10-point visual analogue scale ranging from no pain to the worst pain imaginable. Data are available for 74 patients undergoing cataract surgery under peribulbar anaesthesia and for 55 patients in whom sub-Tenon's anaesthesia was used. Pain scores for administration of anaesthetic were significantly lower (Kruskal-Wallis H-test, p < 0.01) for sub-Tenon's anaesthesia (mean 1.4) compared with the peribulbar technique (mean 2.4). However, a similar number of patients experienced pain of greater than 3 for the two techniques (10 (18.5%) for sub-Tenon's and 14 (18.9%) for peribulbar). Per-operative pain scores for sub-Tenon's anaesthesia (mean 0.5) were lower than those for peribulbar anaesthesia (mean 1.2) but not significantly so (Kruskal-Wallis H-test, p = 0.073). Significantly fewer patients, however, experienced pain of greater than 3 (Fisher exact test, p < 0.05) in the sub-Tenon's group. In addition less anaesthetic solution and a shorter interval from administration to surgery was required in the sub-Tenon's group. Sub-Tenon's anaesthesia appears to be a more effective method of anaesthesia than the peribulbar method.