Conscious sedation for cataract surgery done under retrobulbar block – a comparative study evaluating the effects of midazolam and dexmedetomidine

A comfortable co-operative stationary patient is essential for cataract surgery especially under retrobulbar block. This can be achieved by placing the patient under ‘conscious sedation’ in which the patient will be arousable but at the same time can tolerate pain.

To compare the efficacy of midazolam with dexmedetomidine for conscious sedation in cataract surgery with regard to anxiolysis, patient's cooperation, haemodynamic stability, surgeon's satisfaction, recovery profile and incidence of complications.

90 adult patients undergoing cataract surgery were randomized to three groups. Group M (n=30) patients received midazolam in loading dose of 0.03mg/kg over 10 minutes and a maintenance dose of 0.05mg/kg/hr. Group D (n=30) patients received dexmedetomidine in loading dose of 0.3mcg/kg over 10 minutes and a maintenance dose of 0.3μg/kg/hr. Group C (n=30) are control group receiving normal saline infusion as loading and maintenance doses. Statistical analysis was done using Chi-square test and ANOVA test with p value <0.05 taken as statistically significant.

Anxiolysis, patient comfort and surgeon's satisfaction were better in midazolam and dexmedetomidine groups when compared to the control group. In dexmedetomidine group there were significant incidences of hypotension and bradycardia when compared to midazolam group. Time to achieve sedation was faster in the dexmedetomidine group than in the midazolam group.

Midazolam and dexmedetomidine are effective in the aspects of patient co-operation, surgeon's comfort, sedation and recovery profiles, and is safe to administer in cataract surgeries.