Effects of increasing enflurane concentrations on intraocular pressure

The effects of enflurane at various concentrations on intraocular pressure (IOP) were studied. In 15 healthy patients, intubated and mechanically ventilated, IOP was measured the day before surgery, after premedication and during anaesthesia, after administration of 0.5%, 1.0% or 1.5% enflurane. Enflurane in combination with general anaesthesia and controlled ventilation (PCO2 4.7-5.3 kPa) caused a significant decrease in IOP. The decrease was more marked (44%) with 1% enflurane than with 0.5% enflurane (21%). The change in IOP was comparable with 1.0% and 1.5% enflurane; however, systolic arterial pressure decreased more with enflurane 1.5%. Increasing the inspired concentration of enflurane from 1% to 1.5% did not appear to be associated with any further decrease in IOP.