Comparison of the effects of isoflurane and halothane on intraocular pressure

Intraocular pressure (IOP) was measured in four groups of patients receiving isoflurane or halothane in consecutively increasing or decreasing concentrations (1.0, 2.0 and 3.0 MAC in 70% nitrous oxide). IOP decreased significantly in all groups irrespective of whether the higher or the lower concentration of the volatile agent was used first. There were no further significant changes in IOP whether the concentrations were increased or decreased, suggesting no dose-relation. Maximum reductions in IOP were slightly greater in those receiving the higher concentrations of the volatile agents first (64 and 66% with isoflurane and halothane, respectively) in comparison to those receiving the lower concentrations first (54 and 46%, respectively).