Intraocular pressure during enflurane and neurolept anesthesia in adult patients undergoing ophthalmic surgery

The effects of neurolept and enflurane anesthesia on intraocular pressure (IOP) were studied in 20 patients undergoing elective ophthalmic surgery. Ten received neurolept and ten enflurane anesthesia. Continuous EEG tracings recorded the level of anesthesia. IOP was measured before and at intervals during anesthesia at varying concentrations of enflurane and incremental doses of fentanyl. During level I neurolept anesthesia IOP increased from control values of 18.10 +/- 0.93 mm Hg (mean +/- SEM) to 19.50 +/- 1.65 mm Hg, but decreased to 14.55 +/- 0.84 mm Hg during level II and to 12.29 +/- 1.13 mm Hg during level III anesthesia. During enflurane anesthesia IOP decreased from control values of 19.00 +/- 1.44 mm Hg (mean +/- SEM) to 14.50 +/- 1.60 mm Hg during level, I, 14.10 +/- 1.04 mm Hg during level II, and 11.60 +/- 1.46 mm Hg during level III anesthesia. The increase in IOP during neurolept level I anesthesia was not statistically significant but the decreases in IOP from control values during levels II and III anesthesia were statistically significant. Decreases in IOP from control values were statistically significant at all levels of enflurance anesthesia. There was, however, no statistical significance between the differences in IOP values during levels II and III neurolept anesthesia, nor between levels I, II, and III enflurane anesthesia. The differences in the mean IOP values between neurolept and enflurane anesthesia were statistically significant only during EEG level I anesthesia.