Pulse-induced intraocular pressure variation and retrobulbar anaesthesia with and without adrenaline

The intraocular pressure (IOP) and pulse-induced IOP variation (IOPV) were registered before and five min after retrobulbar anaesthesia (RBA) in 34 operations. The every second operation the anaesthetic (bupivacaine or lidocaine) was supplemented with adrenaline (epinephrine). Both IOP and IOPV were significantly lowered compared with the unanaesthetised fellow eye. The change in IOP was 16,8% with adrenaline and 15.1% without it. IOPV decreased 50.6% with adrenaline and 36.2% without adrenaline. It is concluded that RBA reduces the intraocular blood supply and this is probably one reason for the IOP lowering influence of RBA. Although to a smaller degree, this vascular effect is also achieved without adrenaline.