Measurement of tear production and intraocular pressure in conscious captive European fallow deer (DAMA dama)

Abstract

Normal values for intraocular pressure (IOP) and tear production in conscious cervids have not been reported to date. Based on trends in zoological institutions to perform non‐anaesthetized health exams, it is applicable to establish normal values in conscious animals, as anaesthesia and sedation can alter these parameters. The goal of this study was to estimate intraocular pressures using rebound tonometry and measure tear production values in a group of healthy, conscious, European fallow deer utilizing chute restraint. Evaluation of these values with regards to instrumentation and restraint variables will be assessed. Complete ophthalmic examinations, including estimation of IOP with rebound tonometry and measurement of tear production with Schirmer tear tests (STT) were performed on nine conscious European fallow deer (Dama dama) restrained in a chute. Correlations between IOP on the unspecified (P) and the equine (H) settings, as well as IOP and STT differences between left (OS) and right (OD) eyes were evaluated, in addition to assessment of correlations between right and left lateral recumbency on IOP and STT. Tear production measurements were 18.7 ± 5.1 mm min−1 with a 95% confidence interval (CI) range of 16.4–21.1 mm min−1. Intraocular pressure measurements for the P setting were 16.1 ± 4.5 mmHg with a 95% CI range of 14.1–18.2 mmHg, and for the H setting were 21.5 ± 5.1 mmHg with a 95% CI range of 19.1–23.9 mmHg. No statistically significant difference (P > 0.05) was found between OS and OD in any test. Neither left nor right lateral recumbency was found to have a statistically significant effect on IOP or STT. This study represents the first assessment of ophthalmic parameters in conscious fallow deer with rebound tonometry and STT.

Measurement of Tear Production and Intraocular Pressure in Clinically Conscious Normal Captive Red Deer (Cervus elaphus)

“…Studies show that, even within the same family, STT values can be highly variable; also, the methodology is different. There are STT data on conscious, manually restrained European fallow deer ( Dama dama ): An average STT of 18.7 ± 5.1 mm/min and 17.8 ± 3.16 mm/min [ 8 , 12 ]. These values were higher than in manually restrained brown brocket deer ( Mazama gouazoubira ) (8.9 ± 1.8 mm/min) and similar to in sambar deer ( Rusa unicolor ) (STT 18.8 ± 4.7 mm/min), but higher than in anaesthetised Persian fallow deer ( Dama mesopotamica ) (STT 10.5 ± 6.5 mm/min) [ 12 , 13 , 14 , 15 ].…”

“…Within the deer family, IOP is also varying. In conscious European fallow deer that were manually restrained, IOP was 21.5 ± 5.1 mmHg on the H (horse) setting [ 12 ], measured with an applanation tonometer; for sambar deer, it was only 11.4 ± 2.8 mmHg [ 14 ]. By comparison, in sedated Persian fallow deer and white-tailed deer ( Odocoileus virginianus ), IOP was 11.9 ± 3.3 mmHg, measured by an applanation tonometer, and 12.87 ± 2.57 mmHg when measured with a rebound tonometer, which is lower than our results [ 11 , 13 ].…”

“…Thus far, there have been limited studies giving the normal values of STT and IOP in wild ruminants. There are data on the captive mouflon, Alpine ibex, Alpine chamois, captive eland, Nubian ibex [ 8 , 9 , 10 ], fallow deer, and white-tailed deer [ 11 , 12 ]. However, there are differences in methodology between these studies: For example, examining animals under anaesthesia or physical restraint; or measuring IOP with different tonometers (applanation or rebound) [ 13 , 14 , 15 ].…”

Schirmer’s Test I and Determination of Intraocular Pressure in Healthy Common Buzzards (Buteo buteo)

“…Intraocular pressure (IOP) is another important parameter used to evaluate eye diseases in birds, such as glaucoma and uveitis [19]. Two types of measurement methods applanation and rebound tonometry each of which requires a different type of device are used to measure IOP [8]. Rebound tonometry is the commonly preferred method in veterinary medicine because of its practicality and because no topical anesthetic is needed, and the TonoVet® rebound tenometer, which has a magnetic probe on its tip, is used for this procedure [12].…”