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

Abstract

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 15IU/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 vs 1.65 mm, P-value 0.01 and 0.43 vs 1.52 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.