Effects of Ketamine Anesthesia on Intraocular Pressure in Cynomolgus Monkeys

Abstract

Effects of ketamine hydrochloride anesthesia on the intraocular pressure-reducing effect of timolol maleate were evaluated in male cynomolgus monkeys of 5-6 years of age. Intraocular pressure (IOP) was measured following several minutes after ketamine hydrochloride anesthesia at each measurement interval.

A statistically significant or slight increase in IOP was noted in anesthetized animals as compared to conscious animals. After instillation of timolol maleate, IOP was measured under ketamine hydrochloride anesthesia. IOP values in animals anesthetized at 5 mg/kg were comparable to those in conscious animals; whereas, the values were more decreased in animals anesthetized at 10 mg/kg as compared to those in animals anesthetized at 5 mg/kg and in conscious animals.

An increase in dose level of ketamine anesthetic enhanced the IOP-reducing effect of timolol maleate and individual differences in the depth of anesthesia resulted in appreciable variations in IOP. Therefore, determination of IOP in monkeys is considered to be desirable to be conducted using well-trained conscious monkeys.