A COMPARATIVE STUDY OF INTRAOCULAR PRESSURE AND GROSS OUTFLOW FACILITY IN CAT EYE DURING ANESTHESIA

Intraocular pressure and gross facility were measured in cats anesthetized with pentobarbital, urethane, chloralose/urethane and halothane. Intraocular pressures measured in animals under urethane, chloralose/urethane and halothane anesthesia were similar (about 19 mmHg); in contrast, a lower steady-state intraocular pressure in the order of 14 mmHg was found under pentobarbital anesthesia. Gross outflow facility estimated by analysis of pressure decay curves and the constant rate infusion method was also found to depend upon the anesthetic agent used. The values for outflow facility were found to be lowest under halothane and highest under pentobarbital anesthesia. Pentobarbital was also shown to have a direct effect on outflow facility; in addition, the results suggest that pentobarbital may depress the formation of aqueous humor. Both the constant rate infusion and pressure decay curve techniques were found to be unsuitable for repeated estimations of outflow facility in the same eye since they yielded increasing values for outflow facility; in contrast, the constant pressure method was found to yield reasonably stable successive values for outflow facility. It is concluded that care should be taken in the choice of anesthetic agent for use in experiments on intraocular pressure, and the possible effects of the anesthetic agent itself should be considered in the interpretation of the results. © 1969 Academic Press Inc. (London) Limited.