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  • 1
    ISSN: 1432-1351
    Keywords: Brown kiwi ; Apteryx australis ; Accommodation ; Photorefraction ; Corneal curvature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Brown kiwis are an endangered species of nocturnal, flightless birds which are native to New Zealand. The resting focus of two specimens has previously been studied by retinoscopy in a zoo while the birds were restrained by their keeper (Sivak and Howland 1987). Those birds appeared to be hyperopic (farsighted) by 2–7 D. In this study, examination with infrared photorefraction of the focusing of two unrestrained, feeding birds showed that they could focus objects at infinity and objects in their immediate environment and that they had modest powers of accommodation. Measurements on two 6 month old kiwi chicks showed their corneal radius of curvature to be between 2.90 and 3.00 mm (117 D and 101 D in power).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1351
    Keywords: Photorefraction ; Accommodation ; Tytonidae ; Near vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an examination of the focusing abilities of 15 species of owls, the North American barn owl, Tyto alba pratincola (Bonaparte 1838), was an outstanding accommodator, having a range of accommodation exceeding 10 diopters (Murphy and Howland 1983). Using comparable methods, we examined the accommodation of 4 specimens of the Australian barn owl, Tyto alba delicatula (Gould 1837). We failed to elicit accommodation greater than two diopters, and most stimuli failed to evoke any discernable accommodation at all. Furthermore, examination of other Australian tytonid owls, the grass owl, T. longimembris, the sooty owl, T. tenebricosa, and both the mainland and Tasmanian subspecies of the masked owl, T. novaehollandiae novaehollandiae and T. novaehollandiae castanops, also failed to reveal anything but very moderate accommodative ranges. We conclude that the outstanding accommodative ability of the American barn owl is truly an exception to the modest accommodative abilities of the tytonid owls generally.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1351
    Keywords: Tuatara ; Sphenodon punctatus ; Accommodation ; Photorefraction ; Corneal curvature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Photorefraction and photokeratometry were performed on two juvenile tuatara (Sphenodon punctatus, 7 years of age, total length approx. 27 cm). Sphenodon is the only surviving genus of the Rhynchocephalia, an order of reptiles. Both existing species are endangered and are found only in New Zealand. Even though Walls (1942) has stated that the ciliary muscle is relatively weak in tuataras, we observed 8 D of accommodation. The eyes were found to focus independently and we could induce an anisometropia of 6 D. The average corneal power of the tuatara was found to be 101 D.
    Type of Medium: Electronic Resource
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