Lidocaine-clonidine retrobulbar block for cataract surgery in the elderly

Clonidine, an alpha-2-adrenoreceptor agonist, has been shown to decrease intraocular pressure (IOP) and to have some analgesic and sedative effects when it is used in premedication for ophthalmic surgery. This study was designed to investigate the efficacy of lidocaine-clonidine retrobulbar block for cataract surgery with respect to its effect on IOP, analgesic action, and sedative effects.

Sixty elderly patients (ASA status I and II) were allocated randomly to receive in a prospective double-blind manner retrobulbar block for cataract surgery. Group I (n = 30) received 3-4 mL of 2% lidocaine with 1 mL saline, while group 2 (n = 30), received 3-4 mL of 2% lidocaine with clonidine 2 micrograms/kg.

A large decrease in intraocular pressure from 13.5 +/- 4.6 to 7.7 +/- 3.7 mm Hg (P < .01) and a small but significant reduction of both systolic and diastolic blood pressure were observed 20 minutes alter the retrobulbar block in patients receiving clonidine, while no changes occurred in the control group. The median duration of analgesia and akinesia was greater in the lidocaine-clonidine group (241 +/- 88 minutes and 80 +/- 20 minutes, respectively) as compared with the lidocaine group (128 +/- 24 minutes and 70 +/- 20 minutes, respectively) (P < .01, P < .05). Sedation scores were greater in group 2 from the 10-minute point (P < .01).

Addition of clonidine to lidocaine for retrobulbar block causes a decrease in intraocular pressure, a sedative effect, and an increased duration of analgesia and akinesia, with relatively stable hemodynamic parameters.