An Eagle's Eye: Quality of the Retinal Image

  title={An Eagle's Eye: Quality of the Retinal Image},
  author={Robert Shlaer},
  pages={920 - 922}
  • R. Shlaer
  • Published 26 May 1972
  • Medicine
  • Science
The optical quality of a living eagle's eye was determined by an ophthalmoscopic method. The performance of the eye was substantially better than that reported for humans, but did not confirm some of the wilder claims made for such birds. 

Retinal image quality in the rodent eye

Using the measurements of the optics and the published behavioral and electrophysiological contrast sensitivity functions of rats, the CSF that the rat would have if it had perfect rather than poor optics is calculated.

Ocular Optical Filtering

The purpose of this chapter is to review the effects of optical filtering on eye function emphasizing such unresolved issues, for example, as the function of optical filters in the eyes of animals with high (suprahuman) visual acuity.

Falcon visual sensitivity to grating contrast

It is reported that the cut-off frequency (a measure of visual acuity) is twice the expected value and is the same for kestrel and human eyes.

The role of the limbal cornea in vision

The studies showed the eagle cornea to be thinner, scatter less light and be more spherical than the human cornea, and it is recommended that optical iridectomy be considered, in appropriate cases of corneal blindness with patches of clear peripheral cornea when no donorCorneal material is available.

An owl's eye: Schematic optics and visual performance inStrix aluco L.

  • G. Martin
  • Biology
    Journal of comparative physiology
  • 2004
The schematic eye ofrix aluco, a nocturnal owl species, is described and it is concluded that the essentially ‘nocturnal’ feature of the owl eye does not lie in either its light gathering power or the sensitivity of individual rod receptors.

Telephoto lens system of falconiform eyes

It is shown here that the presence of a spherical depression in the deep fovea of falconiforms may act like the negative lens component in a telephoto lens system or opera glass, thus providing the relatively large images necessary for more complete image reconstruction in a localised region of the retina.

The refractive development of the eye of the American kestrel (Falco sparverius): a new avian model

This study is the first indication that chickens may not be a representative bird model for studying form deprivation myopia, and kestrels are severely myopic at hatching and therefore, the direction of emmetropization is opposite to that found in hatchling chicks.

Fundamentals of spatial vision in the barn owl (Tyto alba pratincola) : ocular aberrations, grating acuity, contrast sensitivity, and vernier acuity

Optical quality in barn owl eyes is presented in terms of measuring the ocular wavefront aberrations with a standard Tscherning-type wavefront aberrometer under natural viewing conditions and the results suggest that image quality in Barn Owl eyes is excellent.

Avian mechanisms for vision in air and water

  • J. Sivak
  • Physics
    Trends in Neurosciences
  • 1980

Critical limiting factors in the design of the eye and visual cortex

Three stages of dealing with the visual image are proposed: the improvement of the cortical map in primary visual cortex by processes analogous to spatial and temporal interpolation; the detection of linking features in this map; and the concentration of this information by non-topographical mapping in adjacent visual areas.




  • S. Shlaer
  • Physics
    The Journal of general physiology
  • 1937
The relation of visual acuity and illumination for two trained observers was measured and the conclusion that detail perception is a function of a distance rather than an area is made.


Measurements with the C show that when intensity discrimination at the retina is experimentally made the limiting factor in resolution, visual acuity is improved by conditions designed to increase image contrast, but intensity discrimination cannot be the limiting factors for the ordinary test object resolution.

Spherical aberration and the information content of optical images

  • G. BlackE. H. Linfoot
  • Physics
    Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences
  • 1957
The main purpose of the paper is to investigate the effect of spherical aberration on the information content of low-contrast photographic images with specified spread and noise characteristics. In §


  • T. Henderson
  • Medicine
    The British journal of ophthalmology
  • 1943
The list of conditio'ns which Major Wright indicates may be included in Parinaud's oculoglandular syndrome lends support to his view that this syndrome is liberal in its clinical confines; it would seem that such a label can' add little information to a particular case.

Treatise on Physiological Optics

A composite thin film resistor is disclosed, including an electrically inert substrate upon which is deposited a nickel-chromium alloy thin film, and an overlying second thin film - which is initially deposited as metallic tantalum - which provides a very high degree of environmental protection with respect to the Ni-Cr film.

The Retina (Univ. of Chicago Press, Chicago, 1941); The Vertebrate

  • Visual System (Univ. of Chicago Press,
  • 1957

The Vertebrate Eye (Cranbrook Institute

  • 1942