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Abstract #15631 Published in IGR 2-3
Effect of general anesthetics on IOP in rats with experimental aqueous outflow obstruction
Jia L; Cepurna WO; Johnson EC; Morrison JCInvestigative Ophthalmology and Visual Science 2000; 41: 3415-3419
PURPOSE: To determine the effect of several common general anesthetics on intraocular pressure (IOP) after experimental aqueous outflow obstruction in the rat. METHODS: A single episcleral vein injection of hypertonic saline was used to sclerose aqueous humor outflow pathways and produce elevated IOP in Brown Norway rats. Animals were housed in either standard lighting or a constant low-level light environment. Awake IOPs were determined using a TonoPen (Mentor, Norwell, MA) immediately before induction of anesthesia by either isoflurane, ketamine, or a mixture of injectable anesthetics (xylazine, ketamine, and acepromazine). For each anesthetic, IOPs were measured immediately after adequate sedation (time 0) and at five-minute intervals, up to 20 minutes. RESULTS; Awake IOPs ranged from 18-52 mmHg. All anesthetics resulted in a statistically significant (p < 0.01) reduction in measured IOP at every duration of anesthesia when compared with the corresponding awake IOP. With increasing duration of anesthesia, measured IOP decreased approximately linearly for both the anesthetic mixture and isoflurane. However, with ketamine, IOP declined to 48 ± 11% (standard lighting) and 60 ± 7% (constant light) of awake levels at five minutes of anesthesia, where it remained stable. In fellow eyes, the SD of the mean IOP in animals under anesthesia was always greater than the corresponding SD of the awake mean. Anesthesia's effects in normal eyes and eyes with elevated IOP were indistinguishable. CONCLUSIONS: All anesthetics resulted in rapid and substantial decreases in IOP in all eyes and increased the interanimal variability in IOPs. Measurement of IOP in awake animals provides the most accurate documentation of pressure histories for rat glaucoma model studies.
Dr. L. Jia, Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health Sciences University, Portland, OR 97201, USA
Classification:
5 Experimental glaucoma; animal models
12.17 Anesthesia (Part of: 12 Surgical treatment)
