Episcleral venous pressure in normotensive and glaucomatous beagles

Episcleral venous pressure was measured by a noninvasive method with a modified force-displacement transducer in six laboratory-quality normotensive and 12 glaucomatous beagles. The dogs were anesthetized by ketamine-xylazine, acepromazine-ketamine, and halothane. Simultaneous intraocular pressure (IOP) and blood pressure were recorded. The mean episcleral venous pressures in normotensive beagles were 11.4 to 11.6 mm Hg with the three methods of anesthesia; in the glaucomatous beagles the mean episcleral pressures were 10.6 to 12.5 mm Hg. There were no significant differences in episcleral venous pressure (p less than 0.19 and greater) and blood pressure (p less than 0.53 and greater) between the normotensive and glaucomatous beagles. IOP was significantly different between the normotensive and glaucomatous beagles anesthetized with acepromazine-ketamine (mean IOP, 23.4 and 34.2 mm Hg, respectively; p less than 0.02) and halothane (mean IOP, 19.9 and 27.4 mm Hg, respectively; p less than 0.001) but not significant with anesthesia with ketamine-xylazine (mean IOP, 26.0 and 37.8 mm Hg, respectively; p less than 0.12). Episcleral venous pressure is unchanged as the disease progresses in the glaucomatous beagle.