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Lower-field myopia in birds: An adaptation that keeps the ground in focus

Hodos, W. and Erichsen, Jonathan Thor 1990. Lower-field myopia in birds: An adaptation that keeps the ground in focus. Vision Research 30 (5) , pp. 653-657. 10.1016/0042-6989(90)90091-X

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In the lower visual field of pigeons, a myopia (near-sightedness) has been reported that progressively increases with the angle below the horizon. Previous data suggested that this lower-field myopia may be an adaptation that permits pigeons to keep the ground in focus while they forage, and simultaneously, to monitor the horizon and sky for predators. We report here a lower-field myopia in other species of birds that have a wide range of heights. A geometric model of this adaptation predicts that the amount of myopia should be systematically related to the distance from the pupil to the ground. The eyes of quail, chickens and cranes of various heights (7.0–104.1 cm) were refracted at 60 deg below the horizon. Their myopia was close to the predicted value at each height.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Optometry and Vision Sciences
Subjects: R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
R Medicine > RE Ophthalmology
Uncontrolled Keywords: Refraction; Physiological optics; Visual fields; Myopia; Birds
Publisher: Elsevier
ISSN: 0042-6989
Last Modified: 04 Jun 2017 03:11

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