Intraocular Pressure and Tear Production in Captive Eland and Fallow Deer

Ofri, Ron; Horowitz, Igal; Levison, M.; Kass, Philip H.

doi:10.7589/0090-3558-37.2.387

Cited by 29 publications

(42 citation statements)

References 8 publications

(7 reference statements)

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“…Hence, it is likely that the mechanism driving increased pressure in winter is partial or complete blockage of the trabecular meshwork by the iris folding over it. The pressures obtained here for summer animals of approximately 13 mmHg are similar to those found in other members of the cervidae family [16]. Hence, raised winter pressure of about 18 mmHg is a seasonal deviation from the normal pattern.…”

Section: Discussionsupporting

confidence: 83%

Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer

et al. 2013

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Arctic reindeer experience extreme changes in environmental light from continuous summer daylight to continuous winter darkness. Here, we show that they may have a unique mechanism to cope with winter darkness by changing the wavelength reflection from their tapetum lucidum (TL). In summer, it is golden with most light reflected back directly through the retina, whereas in winter it is deep blue with less light reflected out of the eye. The blue reflection in winter is associated with significantly increased retinal sensitivity compared with summer animals. The wavelength of reflection depends on TL collagen spacing, with reduced spacing resulting in shorter wavelengths, which we confirmed in summer and winter animals. Winter animals have significantly increased intra-ocular pressure, probably produced by permanent pupil dilation blocking ocular drainage. This may explain the collagen compression. The resulting shift to a blue reflection may scatter light through photoreceptors rather than directly reflecting it, resulting in elevated retinal sensitivity via increased photon capture. This is, to our knowledge, the first description of a retinal structural adaptation to seasonal changes in environmental light. Increased sensitivity occurs at the cost of reduced acuity, but may be an important adaptation in reindeer to detect moving predators in the dark Arctic winter.

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Section: Discussionsupporting

confidence: 83%

Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer

et al. 2013

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“…However, results for the TonoVet‐D calibration are similar to those obtained for dogs 37 . Tono‐Pen XL ® measurements in the pygmy goats are lower than means and ranges reported from most other animals, with the exceptions of Thomson gazelles, impalas, and some birds 29,36,38–55 . Regardless, the range for Tono‐Pen XL ® measurements broadly overlaps with most other animals.…”

Section: Discussionsupporting

confidence: 69%

Ophthalmic examination findings in adult pygmy goats (Capra hicus)

Broadwater

Schorling

Herring

et al. 2007

Veterinary Ophthalmology

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“…The following mean IOP were reported with applanation tonometry: 19.2 ± 5.9 mm Hg in dogs, 19.7 ± 5.6 mm Hg in cats, 23.3 ± 6.89 mm Hg in horses, 26.9 ± 6.7 mm Hg in dairy cattle, 14.6 ± 4.0 mm Hg in elands, 11.9 ± 3.3 mm Hg in the deers, 13.10 ± 0.35 in llamas, 14.85 ± 0.45 mm Hg in alpacas, 9.35 ± 1.81 mm Hg in Eurasian Eagle owls, 7.6 ± 1.6 mm Hg in Thomson gazelle and 24·9 ± 2·0 mm Hg in male lions (Miller et al, 1990;Gum et al, 1998;Ofri et al, 1999;Ofri et al, 2000;Willis et al, 2000;Ofri et al, 2001;Jeong et al, 2007;Rusanen et al, 2010). Our study showed that the mean IOP of sheep was lower than those of dogs, cats, horses, dairy cattle and lions, although it was higher than in the eland, deers, llamas, alpacas, owls and Thomson gazelle.…”

Section: Discussionmentioning

confidence: 99%

Intraocular pressure measurement in sheep using an applanation tonometer

Pigatto¹,

Pereira

Albuquerque

et al. 2011

Rev. Ceres

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RESUMO Mensuração da pressão intraocular em ovinos, usando tonômetro de aplanaçãoO objetivo deste estudo foi avaliar e estabelecer os valores de pressão intraocular (PIO) média, em ovinos adultos saudáveis, usando a tonometria de aplanação. Foram utilizados no estudo 25 ovinos saudáveis (Ovis aries), da raça Texel, machos ou fêmeas de três anos de idade. Foram realizados exames oftálmicos, incluindo: avaliação dos reflexos pupilares, teste lacrimal de Schirmer, avaliação com lâmpada de fenda e coloração com fluoresceína, em ambos os olhos de todos os animais. Para a realização dos testes oftálmicos, os animais foram contidos pelo mesmo auxiliar, sem pressão na região jugular e as pálpebras foram delicadamente abertas. A PIO foi aferida, utilizando-se o tonômetro de aplanação Tonopen XL, tendo sido todos os exames realizados pelo mesmo examinador. Foram realizadas três avalia- The purpose of this study was to evaluate and establish the mean values of IOP in healthy adult sheep using an applanation tonometer. Information on age, sex, and breed was obtained for all animals included in this study. Twenty five healthy sheep (Ovis aries), of the same breed (Texel), male or female, with three years of age, received an ophthalmic examination in both eyes, including pupillary reflexes, Schirmer tear test, slit lamp biomicroscopy, and fluorescein staining. For all ophthalmic testing, animals were gently physically restrained, with no pressure in the jugular area and the eyelids were carefully open. IOP was measured by applanation tonometry (Tonopen XL). The same examiner performed the tonometry; measurements were taken three times for each eye, and their average was recorded as the IOP of the animal. Statistical analysis was performed using paired t-test and values of P < 0.05 were considered significant. The mean intraocular pressure in the whole group of 50 eyes was of 16.36 +/-2.19 mm Hg. The mean (SD) IOP in the right eye was of 15.96 +/-2.02 mm Hg, while the mean (SD) IOP in the left eye was of 16.76 +/-2.32 mm Hg. Significant differences in IOP were not found between right and left eyes. The applanation tonometer was adequate for measuring the intraocular pressure in sheep. Reference data will assist in diagnosing testing for ophthalmic disease in sheep, as 1 well as promote further studies in this area.

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Intraocular Pressure and Tear Production in Captive Eland and Fallow Deer

Cited by 29 publications

References 8 publications

Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer

Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer

Ophthalmic examination findings in adult pygmy goats (Capra hicus)

Intraocular pressure measurement in sheep using an applanation tonometer

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