The effect of hyaluronidase on ultrasound-measured dispersal of local anaesthetic following sub-Tenon injection.

PURPOSE

To determine by B-scan ultrasonography if the addition of hyaluronidase affects the dispersal of anaesthetic fluid after sub-Tenon's injection.

DESIGN

Single-centre prospective randomised double-blind study.

MATERIALS AND METHODS

We performed a trial in 19 patients who were randomised to receive 5 ml of lidocaine 2% alone, or with hyaluronidase 15 IU/ml. A pre-anaesthetic B-scan ultrasound was performed followed by a standard infero-nasal sub-Tenon's injection. Further B-scan ultrasound studies were performed at 1, 3, and 5 min recording depth of local anaesthetic fluid. Data was analysed with Fisher's exact test and Student's t-test where appropriate. Results were considered significant when P<0.05.

RESULTS

The maximum depth of local anaesthetic was significantly less in the hyaluronidase group than the control group at 3 and 5 min (0.79 vs1.65 mm, P-value 0.01 and 0.43 vs1.52 mm, P-value 0.002 respectively). There were no statistically significant differences in the akinesia, pain and surgical satisfaction scores between the two groups.

CONCLUSIONS

The addition of hyaluronidase significantly augments the dispersal of local anaesthetic fluid, as measured by B-scan ultrasonography.