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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 3 (1987), S. 0 
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We provided a water-cornea interface to correct the usual aerial myopia encountered in fundus photography of marine mammal eyes. The 12 Tursiops eyes were consistent for vascular structure, optic papillae, dimensional components and tapetal coloration. Multiple photographs were assembled to produce one ocular fundus typical of Tursiops truncatus and one for Grampus griseus. The eyes have a vestigial hyaloid vessel and an optic disc („blind spot”) that occupies the center of the fundus. The disc is bounded in both species by a vascular structure that is continuous with a (retrobulbar) perineural organ called the ophthalmic rete. The vascular trees of the fundus do not suggest an area of specialization for high resolution. Both species exhibit total tapetalization. Tapetal spectral reflectance did not vary between Tursiops. There was, however, a difference between species in the short wavelength regions of the spectrum.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 8 (1992), S. 0 
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the laboratory, intraocular pressure (IOP) was measured in each eye of two adult Tursiops truncatus and one Grampus griseus. Measures were made in alternation between eyes over a time span. Means and standard deviations were calculated. Mean IOP's ranged from 33.4 mm Hg (SD = 2.4) in the male Tursiops to 24.6 (SD = 2.3) in the female Tursiops. IOP in the Grampus was intermediate. Tonograph functions for the Tursiops over periods greater than 25 min had a cyclic character with maxima and minima. These cycles were fitted with a polynomial function with periods of 15 min (female) and 20 to 26 min (male). There was no significant correlation of the IOP variations with time between eyes in either Tursiops. Compared to humans, these cetaceans exhibit clinical ocular hypertension bilaterally. The range of pressures they exhibit, over time, is much greater than reported previously for several terrestrial mammals.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 8 (1992), S. 0 
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Details of the lenses of eyes in two living Tursiops truncatus and one Grampus griseus were photographed. In the laboratory the lens cortex could be retro-illuminated by a fundus camera and spatially periodic stria could be visualized, in large part because of the highly developed tapetum of the cetacean eye. Varying spaces were present between the stria. On a three-dimensional basis, the best analogy is the layering of an onion. One photograph was digitized giving good quantification of the sizes of the layers and their number. Similar, but less easily resolved, lens cortex organization has been described frequently in humans as “zones of optical discontinuity.” These have been explained as a periodic temporal consequence of normal aging with layer thickness depending on general health. We found that young cetaceans have few “zones” and older cetaceans have many. Lens zones measurement may be developed to Provide objective data on history of cetacean health and age.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 3 (1987), S. 0 
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Compared to the anterior surface of the normal human cornea, all Tursiops showed pronounced random, local curvature changes typical of old keratitis and scarring. Comparable but less severe findings apply to Zalophus. These irregularities were superimposed on the mild regular astigmatism of the spoon-shaped Tursiops cornea (mean central power is 26.8 D, SD = 3.8, N = 82). All Zalophus corneas showed no reliable regular astigmatism (overall mean power is 21.7 D, SD = 4.4, N = 53) but exhibited a flat, circular region about 6.5 mm in diameter along the nasal aspect of the horizontal meridian. Refraction through this cornea1 region showed aerial emmetropia, which accounts for equivalent marine and aerial visual resolution in this species.
    Type of Medium: Electronic Resource
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