Effect of low concentrations of nitrous oxide and isoflurane on peak velocity of saccadic eye movements.

Peak velocity of saccadic eye movements was studied in six healthy volunteers who were each given, on separate days, 5% and 10% MAC of nitrous oxide (5% and 10% end-tidal) or of isoflurane (0.06% and 0.12% end-tidal) or air, each gas for 25 min. Subjective assessment following each treatment was also undertaken. No significant difference was found between air and either 5% or 10% nitrous oxide. However, significant differences occurred at 15 and 25 min after 0.06% isoflurane compared with air (P less than 0.05) and highly significant differences were present 5, 15 and 25 min after 0.12% isoflurane when compared with air and nitrous oxide (P less than 0.01). In contrast, there was little difference between the three gases by subjective assessment.