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Editor,—We congratulate Roman et al 1 on their excellent paper on sub-Tenon’s anaesthesia. We concur that it is efficient, safe, and effective and we agree that it is a useful form of supplementary anaesthesia in patients who experience discomfort during topical anaesthesia. However, the issue of sub-Tenon’s anaesthesia in warfarinised patients has not been addressed.
Between July 1995 and December 1996, we performed 34 cataract extractions in warfarinised patients, using sub-Tenon’s anaesthesia. Thirteen of the 34 procedures were performed in patients with prosthetic heart valves who required the maintenance of a high international normalised ratio (INR). Mean INR at the time of surgery was 2.5. No haemorrhagic complications were encountered intraoperatively. The anaesthesia was effective in all cases. A degree of subconjunctival haemorrhage was encountered in all patients despite the application of cautery before conjunctival incision. Twelve eyes suffered subconjunctival haemorrhages involving between two and three quadrants of the conjunctiva. Two eyes had haemorrhage involving more than three quadrants. There were no other anaesthetic related complications.
Warfarinised patients represent a small but significant proportion of those requiring cataract surgery. Stopping warfarin in anticoagulated patients can be hazardous.2 Underlying medical conditions may also make general anaesthesia hazardous. Retrobulbar and peribulbar anaesthesia, although not contraindicated, have obvious dangers. Sub-Tenon’s anaesthesia avoids the potential complications of the aforementioned methods. Subconjunctival haemorrhage was the only adverse effect that we encountered. Haemorrhage from a vortex vein is a theoretical risk of the technique, but has not been reported to date.
While topical anaesthesia offers many of the same safety advantages, sub-Tenon’s anaesthesia has significant advantages over topical anaesthesia in sensitive patients and in eyes which are predisposed to potentially time consuming complications.
We conclude that sub-Tenon’s anaesthesia deserves very serious consideration in all warfarinised patients requiring cataract surgery.
Editor,—I thank Drs Reilly and Logan for their comments on our article. Since the paper has been published we have performed a few cataract extractions in anticoagulated patients. We did not encounter any problems related to the anaesthesia. However, because of a possible massive subconjunctival haemorrhage and theoretical risk of a vortex vein trauma, we prefer to start the cataract surgery under topical anaesthesia with lignocaine irrigation to the anterior chamber (Gill’s technique). As mentioned by Reilly and Logan in some cases (poor pupillary dilatation) the patients may still experience discomfort, we will then supplement the anaesthesia with an intraoperative sub-Tenon’s injection. We would not consider peribulbar or retrobulbar anaesthesia.