Surveillance of adverse events associated with local anaesthesia for cataract surgery in Australia and New Zealand

No consensus exists for the ideal local anaesthesia technique to use for cataract surgery. Each option is associated with its own risk benefit profile. Eye blocks provide good surgical conditions at the risk of complications. Topical techniques carry least risk but are not suitable for all patients. We aimed to collect data prospectively across Australia and New Zealand (NZ) via the Australian and New Zealand Ophthalmic Surveillance Unit. This would provide information on the usage of each technique and an incidence of the various adverse events in a similar fashion to studies of the British Ophthalmic Surveillance Unit. The Flinders Medical Centre Ethics Committee approved this study. It was a 25‐month prospective observational study between June 2012 and June 2014 of cataract surgery in Australia and NZ with regard to severe complications of local anaesthesia. The method of data collection is well described in previous research. The practice questionnaire was returned by 130 ophthalmologists giving a response rate of 41%. The average monthly response rate was 59% of ophthalmologists. The total number of cataract cases performed by respondents was estimated to be 47556 per year. This is made up of 16330 public and 23606 private cases performed in Australia and 3468 and 4152 cases, respectively, for NZ. Table 1 shows the type of anaesthetic technique reported. This study identified 20 complications. All reports came from Australia and none from NZ. Anaesthetists performed 19 of the reported blocks and an ophthalmologist one block. There were 17 reported complications from peribulbar block. There were 10 cases of periorbital haemorrhage. Of these, six patients were taking antiplatelet or anticoagulant therapy. Six cases required surgical lateral canthotomy, and two patients had a poor visual outcome. There were six cases of suspected hyaluronidase reactions. The dose range reported was 37 to 150units/mL of hyaluronidase with a median of 75units/mL. The case of 150units/mL took 4weeks for facial periorbital swelling to resolve. There were no cases of visual loss. There was a single case of globe perforation from a peribulbar block requiring retinal surgery resulting in a good visual outcome. Using the total of 17 reports and an estimate of 34500 cases gives an incident rate of 4.9 per 10000 cases. Of note, three reports were classified by the respondents as a peribulbar technique using a 38‐mm needle and total injectate volumes of 2 to 4mL. There were two reported complications from sub‐Tenon blocks, both were central retinal artery occlusion (CRAO). One case used adrenalin in the injectate. Both cases had poor visual outcome. Using the total of two reports and an estimate of 28400 cases gives an incident rate of 0.7 per 10000 cases. There were two further cases of suspected retinal artery occlusion reported following sub‐Tenon block from a single unit without provision of any further clinical information. This survey showed the practice between Australia and NZ to be very different. The practice in NZ can be summarized as being dominated by sub‐Tenon blocks, with some use of topical techniques in the private sector. There is minimal use of needle blocks and sedation. The NZ practice is very similar to current UK practice data. In contrast, the Australian public sector uses mainly peribulbar and sub‐Tenon blocks whilst the private sector uses mainly peribulbar and topical techniques. Both sectors use high levels of sedation. The reasons for the differences in practice are not clear and it may just represent a divergence in medical practice over time. This study shows that complications for all techniques are low. In the cases of periorbital haemorrhage, despite treatment including lateral canthotomies, there were two cases of poor vision. In cases of suspected hyalauronidase reactions, the manufacturer’s recommended dose of 20units/mL was greatly exceeded in all cases. Central retinal artery occlusion has a multifactorial aetiology. Case series of CRAO have been reported with retrobulbar (six cases) peribulbar (three cases) and sub‐Tenon blocks (three cases). Large UK