Background: No studies compared parenteral dexmedetomidine with its use as an adjuvant to ophthalmic block. We
compared between adding dexmedetomidine to bupivacaine in peribulbar block and intravenous (IV) dexmedetomidine
during peribulbar block for cataract surgery.
Materials and Methods: A prospective, randomized, double-blind study on 90 patients for cataract surgery under peribulbar
anesthesia. Study included three groups; all patients received 10 ml of peribulbar anesthesia and IV infusion of drugs as
follows: Group I: Received a mixture of bupivacaine 0.5% (4.5 ml) + lidocaine 2% (4.5 ml) + normal saline (1 ml) + 150 IU
hyaluronidase + IV infusion of normal saline, Group II: Received mixture of bupivacaine 0.5% (4.5 ml) + lidocaine 2%
(4.5 ml) + dexmedetomidine 50 μg (1 ml) +150 IU hyaluronidase + IV infusion of normal saline and Group III: Received mixture
of bupivacaine 0.5% (4.5 ml) + lidocaine 2% (4.5 ml) + normal saline (1 ml) +150 IU hyaluronidase + IV dexmedetomidine
1 µg/kg over 10 min; followed by 0.4 µg/kg/h IV infusion. We recorded onset, duration of block, Ramsay Sedation Score,
intra-ocular pressure (IOP), hemodynamics, and adverse effects.
Results: There was a significant decrease in the onset of action and increase in the duration of block in Group II as compared
with the Group I and Group III. Mean Ramsay Sedation Score was higher in Group III. The IOP showed a significant decrease
in Group II and Group III 10 min after injection (P < 0.01). Heart rate showed a significant decrease in Group III in comparison
with the two other groups (P < 0.05). Only two patients in Group III developed bradycardia.
Conclusion: Dexmedetomidine as an additive shortens onset time, prolong block durations and significantly decreases the
IOP with minimal side effects. IV dexmedetomidine, in addition, produces intra-operative sedation with hemodynamic stability.