To determine the conditions under which anesthetized pigs can be used in acute noninvasive investigations of ocular hydro- and hemodynamics, the intraocular pressure (IOP) of adult pigs was recorded under the following conditions: (1) after intravenous injection of propofol plus ketamine; (2) during inhalation of isoflurane, and (3) 2 h after topical administration of bimatoprost or (4) timolol. Propofol/ketamine and isoflurane induced significant decreases in the IOP. The pulsation of the ophthalmic artery appeared at a significantly higher IOP in animals anesthetized with isoflurane than in those anesthetized with propofol/ketamine. Bimatoprost and timolol did not significantly decrease the IOP within 2 h after topical administration. It is concluded that different techniques for the acute noninvasive investigation of ocular hydro- and hemodynamics are applicable in anesthetized pigs. To test the effects of antiglaucoma agents, investigation periods longer than 2 h are required. We recommend the use of intravenous propofol/ketamine anesthesia rather than isoflurane anesthesia in future experiments using pigs.

Purpose The aim of this study was to examine the accuracy of the intraocular pressure (IOP) reading of two portable tonometer in the porcine eye in situ. The influence of two anaesthetic techniques on the IOP was analysed. Methods Experiments were conducted in 20 healthy domestic white pigs. After a standard premedication 9 pigs were investigated under a total IV propofol anaesthesia (A) and 11 pigs under an isoflurane inhalation anaesthesia (B). IOP was measured at two different time points: prior to anaesthesia (time 1) and 15 minutes after induction of anaesthesia (time 2). To compare IOP measurements obtained with the digital Tonopen® with those of Schioetz tonometry, one single measurement, generated by Tonopen® tonometer was compared with a single reading from Schioetz tonometer in 11 pigs at time point 1 and 2 (isoflurane anaesthesia). Results A significant decrease in IOP of 13.8 % (A) and of 10.2 % (B) was measured in comparison to baseline IOP prior to general anaesthesia. There was a high significant (r = 0.68; p<.05) correlation at time 1 between the Schioetz and the Tonopen® tonometer but no significant correlation at time 2. Conclusion The significant IOP‐lowering effect of inhalation and total intravenous anaesthesia has to be considered in animal models. We point out that there are established methods for clinical measurements of the IOP but the user should be aware that there are differences in measured IOP when methods are compared.