Objective
To compare sub-Tenon’s block with peribulbar block in patients on oral warfarin therapy undergoing cataract surgery.
Materials and methods
We studied 100 patients on warfarin undergoing cataract surgery; randomly allocated into one of two groups; sub-Tenon’s group (group S,  = 50), and peribulbar group (group P,  = 50). In group (S), sub-Tenon’s injection of 3–5 ml of anesthetic agent was done using a 25 mm sub-Tenon’s cannula. In group (P), the peribulbar block with 3–4 ml of 2% lidocaine–hyaluronidase (10 IU/ml) and 0.5% bupivacaine was done. Pain and akinesia and postoperative complications were assessed.
Results
Sub-Tenon group showed significantly higher frequency of hemorrhage compared to peribulbar group (30% versus 8%,  = 0.041), mainly of grade I. The two groups had comparable frequency of subconjunctival hemorrhage ( = 1.000). No patients experienced sight-threatening hemorrhagic complications. Pain was significantly lower in the sub-Tenon group. Akinesia was significantly better ( = 0.025) 2 min after injection and comparable from 4 to 10 min after injection in the peribulbar group. The majority of patients in the two groups reported satisfaction ( = 0.372). The surgeon expressed higher satisfaction with peribulbar block (94%) compared to sub-Tenon’s block (81%) ( = 0.064).
Conclusion
Peribulbar and sub-Tenon techniques were relatively safe in patients on anticoagulants during cataract operation. We recommend peribulbar technique owing to significantly less bleeding and more satisfactory akinesia response and hence surgeon comfort.