ABSTRACT
The dose response relationship of clonidine added to lidocaine in peribulber block were assessed in 52 adult patients of both sexes, undergoing cataract surgery. They were given 7 mL mixture of 2% lidocaine with clonidine in 0.5 micro g / kg [0.5 Clon]. 1.0 micro g /kg [1.0 Clon] and 1.5 micro g / kg [1.5 Clon] doses and compared to lidocaine alone [control]. The onset and duration of lid and globe akinesia and globe anaesthesia and analgesia, adverse effects [hypotension, bradycardia, hypoxia and sedation] and postoperative analgesic requirement were recorded. The success rate and onset of block were comparable in all groups. The duration of lid and globe akinesia, globe anaesthesia and analgesia was significantly prolonged in patients receiving 1.0 and 1.5 micro g/kg clonidine as compared with the control group [P <0.01]. Perioperative pain score and analgesic requirement were significantly less in these groups, 0.5 micro g/kg clonidine did not significantly increase the duration of anaesthesia and analgesia. Hypotension and dizziness were observed more in patients receiving 1.5 mirco g /kg clonidine as compared to other groups. In conclusion, clonidine 1.0 mirco g / kg mixture with lidocaine [2%] was significantly prolonged the duration of anaesthesia and analgesia after peribulbar block with limited side effects