Background
Peribulbar anesthesia is widely practiced as a safe local block for cataract eye surgeries. Fentanyl has been used as an adjuvant to local anesthetics, prolonging their duration of action. Clonidine has been shown to increase the duration of analgesia and anesthesia produced by local anesthetics.
Aim of the study
The aim of this study was to compare the effect of fentanyl versus that of clonidine when used as adjuvants to bupivacaine in peribulbar block.
Methodology
Ninety patients, ASA physical status I–III, scheduled for cataract operations, under peribulbar block, were enrolled in the study and randomly assigned into 3 equal groups. Group F ( = 30) received a mixture of bupivacaine, hyaluronidase, and fentanyl; Group C ( = 30) received a mixture of bupivacaine, hyaluronidase, and clonidine; and in the control Group B ( = 30), a mixture of bupivacaine, hyaluronidase, and saline was used for peribulbar block. The onset, duration of globe anesthesia, akinesia, and lid akinesia were recorded. Intraoperative and postoperative patient comfort, first time to analgesic request, and any recorded complications due to drugs used were all assessed.
Results
Groups C and F showed significantly faster onset and longer duration of globe anesthesia, akinesia, lid akinesia, and the time to first analgesic request when compared to Group B ( < 0.001). The onset, of lid akinesia was significantly faster in Group C compared to Group B ( < 0.01). Group C showed a significantly longer duration of lid akinesia and globe akinesia compared to Group F ( < 0.01).
Conclusion
The addition of either clonidine or fentanyl to the local anesthetic during peribulbar block results in a faster onset and longer duration of the block with a longer period of postoperative analgesia. The addition of clonidine was found to prolong the duration of the block more than fentanyl.