[Ocular circulatory changes caused by retrobulbar anesthesia with and without added adrenaline]

In 80 patients, retrobulbar anesthesia (RBA; 5 ml of a lidocaine-bupivacaine mixture with hyaluronidase) with or without addition of adrenaline (after-mixing concentration 1:500,000) was performed preoperatively. In 2 examination series, the acute and medium-term effects of RBA on the following ocular circulatory variables were investigated: ocular pulsation volume (PVoc), systolic ciliary and retinal perfusion pressures or blood pressures, respectively (method: oculo-oscillo-dynamography).

RBA with adrenaline: Directly after injection, PVoc was reduced by an average of 49%, the ocular perfusion and blood pressures were lowered by averages of 8.0 and 4.3 mmHg, respectively, and the intraocular pressure (Pio; hand-applanation tonometer) was elevated by 3.5 mmHg. 15 min after injection, PVoc and the ocular perfusion and blood pressures were even slightly more reduced, whereas Pio had reassumed its pre-injection level. RBA without adrenaline: During both time periods after injection, the reduction of PVoc averaged 10% less compared to RBA with adrenaline. The changes in ocular perfusion and blood pressures and in Pio, however, were not significantly different from RBA with adrenaline.

The lowering of PVoc--which variable is determined mainly by the pulsatile choroidal blood flow--in concert with the lowered ciliary perfusion and blood pressures is indicative of a reduced ciliary blood flow during RBA. Because of the decreased retinal perfusion and blood pressures, there is also a higher risk of reduced blood supply to the retina. Only to some degree, the observed inhibitory RBA effects on ocular circulation can be explained by adrenaline, and to an even smaller degree by the only transient Pio elevation.