Schematic eyes for domestic animals*

Coile, D. Caroline; O’Keefe, Lawrence P.

doi:10.1111/j.1475-1313.1988.tb01040.x

Cited by 42 publications

(38 citation statements)

References 26 publications

(19 reference statements)

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“…The average geometrical values measured or estimated during the inflation tests are reported in Table 4. The measured average values of the geometrical data for the porcine comea are close to the values documented by Coile et al [32] and by Smythe [33], which reported 9 mm for the curvature, and 7.75 mm and 6.25 mm, respectively, for the in-plane radii.…”

Section: Discussionsupporting

confidence: 85%

Mechanical Characterization of Porcine Corneas

Boschetti

Triacca

Spinelli³

et al. 2012

Journal of Biomechanical Engineering

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An experimental program has been carried out in order to investigate the mechanical behavior of porcine corneas. We report the results of inflation tests on the whole cornea and uniaxial tests on excised corneal strips, performed on 51 fresh porcine eyes. Uniaxial tests have been performed on specimens cut from previously inflated corneas. The cornea behavior is characterized by means of elastic stiffness, measured on both average pressure-apex displacement and average uniaxial stress-strain curves; and by means of transversal contraction coefficient, peak stress, and failure stress measured on uniaxial stress-strain curves. Uniaxial tests performed on excised strips allowed to measure the anisotropy in the corneal stiffness and to compare the stiffness of the cornea with the one of the sclera. Viscous properties of the cornea have been obtained through uniaxial relaxation curves on excised corneal strips. The relevant geometrical parameters have been measured and, with the aid of the elastic thin shell theory, a stress-strain curve has been derived from the average inflation test data and compared with similar data available in the literature. The experimental system has been developed in view of future applications to the mechanical testing of both porcine and human corneas.

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Section: Discussionsupporting

confidence: 85%

Mechanical Characterization of Porcine Corneas

Boschetti

Triacca

Spinelli³

et al. 2012

Journal of Biomechanical Engineering

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“…PND in turn was estimated as a fixed proportion (59%) of the axial length of the eye for dogs [33], [34]. Axial length was individually measured and ranged from ∼15 mm in young dogs (7 wks) to ∼21 mm in adults; and the corresponding RMF ranged from 0.15 to 0.22 mm/deg similar to a previous report of 0.22 mm/deg in adult dogs [33].…”

Section: Methodssupporting

confidence: 67%

“…RMF (and other optical characteristics) of individual eyes can be calculated from simplified schematic eyes if relevant biometric parameters are known or measurable [19], [33]. We used a simpler alternative which is based on the estimate of the posterior nodal distance (PND) and the formula RMF = 2*π*PND/360, where RMF is given in mm/deg and PND is in mm [34].…”

Section: Methodsmentioning

confidence: 99%

“…We used a simpler alternative which is based on the estimate of the posterior nodal distance (PND) and the formula RMF = 2*π*PND/360, where RMF is given in mm/deg and PND is in mm [34]. PND in turn was estimated as a fixed proportion (59%) of the axial length of the eye for dogs [33], [34]. Axial length was individually measured and ranged from ∼15 mm in young dogs (7 wks) to ∼21 mm in adults; and the corresponding RMF ranged from 0.15 to 0.22 mm/deg similar to a previous report of 0.22 mm/deg in adult dogs [33].…”

Section: Methodsmentioning

confidence: 99%

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Canine Retina Has a Primate Fovea-Like Bouquet of Cone Photoreceptors Which Is Affected by Inherited Macular Degenerations

et al. 2014

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Retinal areas of specialization confer vertebrates with the ability to scrutinize corresponding regions of their visual field with greater resolution. A highly specialized area found in haplorhine primates (including humans) is the fovea centralis which is defined by a high density of cone photoreceptors connected individually to interneurons, and retinal ganglion cells (RGCs) that are offset to form a pit lacking retinal capillaries and inner retinal neurons at its center. In dogs, a local increase in RGC density is found in a topographically comparable retinal area defined as the area centralis. While the canine retina is devoid of a foveal pit, no detailed examination of the photoreceptors within the area centralis has been reported. Using both in vivo and ex vivo imaging, we identified a retinal region with a primate fovea-like cone photoreceptor density but without the excavation of the inner retina. Similar anatomical structure observed in rare human subjects has been named fovea-plana. In addition, dogs with mutations in two different genes, that cause macular degeneration in humans, developed earliest disease at the newly-identified canine fovea-like area. Our results challenge the dogma that within the phylogenetic tree of mammals, haplorhine primates with a fovea are the sole lineage in which the retina has a central bouquet of cones. Furthermore, a predilection for naturally-occurring retinal degenerations to alter this cone-enriched area fills the void for a clinically-relevant animal model of human macular degenerations.

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“…The sheep eye is closely similar in shape, structure, size and optical power to the human eye. Coile and O'Keefe (1988) give overall optical powers of 58-6 D for the sheep and 61-3 D for humans. These closely similar powers have been calculated from optical parameters taken from the physiological optical literature used in preparing schematic eyes.…”

Section: Discussionmentioning

confidence: 98%

The eye of the domesticated sheep with implications for vision

Piggins¹,

Phillips

1996

Anim. Sci.

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The eyes of eighteen female sheep fOvis aries) were refracted and details of inter ocular distance, pupil size, shape and fundus presence recorded. The sheep eyes generally possessed very low hyperopia with little astigmatism, such physiological optics being expected to produce a well focused retinal image for objects in the middle and long distance. No evidence was found for accommodation, which would have produced a well focused ocular image for near objects. A further 10 sheep had their monocular and binocular visual fields measured. The estimated visual field suggests the existence of at least binocular vision, if not the presence of stereopsis. Given the lack of accommodation and a wide inter-ocular distance, it is likely that some degree of stereopsis exists in the animal's middle and long distance vision, but is absent in near vision. These findings support those taken from the animal's neurophysiology and observations of its visually guided behaviour.

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Schematic eyes for domestic animals*

Cited by 42 publications

References 26 publications

Mechanical Characterization of Porcine Corneas

Mechanical Characterization of Porcine Corneas

Canine Retina Has a Primate Fovea-Like Bouquet of Cone Photoreceptors Which Is Affected by Inherited Macular Degenerations

The eye of the domesticated sheep with implications for vision

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