Pulsatile ocular blood flow and intraocular pressure during retrobulbar injection of lignocaine: influence of additives.

PURPOSE

To assess the influence of adrenaline and hyaluronidase on pulsatile ocular blood flow and intraocular pressure changes during retrobulbar anesthesia.

METHOD

Patients undergoing cataract surgery under local anesthesia received a 5-mL retrobulbar injection of lignocaine with either adrenaline, hyaluronidase, or no addition. Continuous pneumotonometry was performed using the OBF tonograph (OBF Labs, Chippenham, UK), which automatically derives pulsatile ocular blood flow values. Measurements were taken before and one minute after injection, and changes were compared between groups to evaluate the effects of changing the constituents of the injection.

RESULTS

There was a marked decrease in pulsatile ocular blood flow during injection in all groups. In the group receiving lignocaine with hyaluronidase, the decrease in pulsatile ocular blood flow (mean -141 microL/min) was significantly less than in either the group receiving lignocaine and adrenaline (mean -249 microL/min) or the group receiving lignocaine alone (mean -245 microL/min). There was no significant change in intraocular pressure in any group.

CONCLUSION

Hyaluronidase appears to lessen the reduction in pulsatile ocular blood flow. Injection volumes of 5 mL need not cause significant intraocular pressure change.