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Mark Vezina, Sylvie Wise, Kelly Tenneson, Martin Bussieres, Timothy Bryant, Elridge Edwards; Comparison of Rebound Tonometry in Sedated and Non-Sedated Non Human Primates (NHP). Invest. Ophthalmol. Vis. Sci. 2013;54(15):1993.
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The Tono-Vet® rebound tonometer is commonly used to measure IOP in lab animals due to its portability, ease of use, quick measurements and no topical anesthesia is required for its use. On ocular toxicology studies, intraocular pressure (IOP) measurements of non-human primates (NHP) are normally performed in sedated animals in order to safely handle them for the procedure. The purpose of this study was to assess the feasibility of obtaining consistent IOP measurements from conscious animals.
Ten conscious male Cynomolgus monkeys (n=20 eyes;) were acclimated to tonometry procedure over a period of five days by holding or placing them in a sling, touching their face repeatedly using leather/kevlar gloves and bringing the instrument near the face. IOP measurements were recorded on three of these acclimation occasions. Baseline measurements were then performed 8x/day on two separate occasions. Values were then compared to those obtained from sedated animals (n=172 eyes).
Mean IOP values in conscious animals were consistent over all occasions (19.78 - 20.13 mm Hg) and variability decreased as animals acclimated to the procedure (±3.42 to ±2.60 mm Hg). As expected, IOP values were higher in conscious animals, as compared to values obtained from sedated animals. An average pressure increase of 15% was observed. The variability in IOP readings between conscious and sedated animals was very similar (within ± 3.5%), despite the difference in the number of eyes compared (20 eyes vs. 172 eyes, respectively). When tonometry was performed 8x/day, mean pressure values were highest during the first daily timepoint. No technicians were injured during data capture on conscious animals.
These results demonstrate that consistent IOP values can be safely obtained from conscious acclimated animals using a Tono-Vet®. This is particularly useful in assessing potential glaucoma therapies, allowing multiple IOP measurements to be performed daily without the pressure decreases associated with sedation and removing the anesthesia-related risk and side effects, reducing the anesthesia-related risk to the animals.
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