Ophthalmic artery pressure during retrobulbar anaesthesia

Ophthalmic artery pressure recordings were performed before and after retrobulbar injection of 4.5 ml Xylocain-Exadrin by the use of Stepanik Arteriotonography. A 50% reduction in ophthalmic artery pulse pressure was found, which correlates well with the corresponding reduction in corneal indentation pulse amplitudes demonstrated by dynamic tonometry. The results demonstrate a shift from pulsatile towards non-pulsatile ocular blood flow. In two of the eight patients a pronounced reduction was also found in ocular perfusion pressure, indicating that retrobulbar anaesthesia may be hazardous in certain cases by initiating a major reduction in ocular blood supply. In order to minimize this hazard in eyes especially vulnerable to a reduction in ocular perfusion pressure, such as glaucomatous eyes, it is probably safest to perform retrobulbar anaesthesia with 2-3 ml of Xylocain 1% without the use of Exadrin (epinephrine).