Efficacy of midazolam addition to local anesthetic in peribulbar block : Randomized controlled trial

Peribulbar block is considered a safe option for patients undergoing cataract surgery. The limited duration of regional eye blocks was shown to be the main problem. The objective of this study was to evaluate the effects of adjuvant midazolam (in two concentrations) to lidocaine in the peribulbar block.

This study included 90 adult patients aged 40-70 years undergoing cataract surgery. Each patient was appointed to one of three groups. Group C received a single injection of a peribulbar block using a combination of lidocaine 2% and hyaluronidase 15 IU/ml, group M1 received a combination of lidocaine 2%, hyaluronidase 15 IU/ml plus midazolam 50 µg/ml and group M2 received lidocaine 2%, hyaluronidase 15 IU/ml plus midazolam 100 µg/ml.

The quality of the peribulbar block showed significant improvement among groups by one-way ANOVA (p = 0.002). The mean onset time of the sensory block was significantly shorter in the M2 and M1 groups (1.66 min and 2.17 min, respectively) compared to the control group C (2.52 min), while the onset of lid and globe akinesia lacked significance between the three groups (p = 0.23 and 0.06, respectively). Significance in mean values was found between the control (C) and M2 groups regarding orbicularis oculi function, digital spear pressure, topical anesthetic sting and the total score (P-values = 0.004, 0.016, 0.033 and 0.001, respectively). The duration of lid akinesia and sensory anesthesia were significantly different between the three groups (P = 0.048 and P<0.001, respectively) whereas the duration of globe akinesia was insignificant (P = 0.432).

Addition of midazolam to local anesthetic significantly improved the quality of peribulbar block, hastened the onset of sensory anesthesia, lid and globe akinesia and increased the duration of analgesia without notable side effects.