Journal of Comparative Physiology A

, Volume 184, Issue 4, pp 361–369

Multifocal lenses compensate for chromatic defocus in vertebrate eyes

  • R. H. H. Kröger
  • M. C. W. Campbell
  • R. D. Fernald
  • H.-J. Wagner
ORIGINAL PAPER

DOI: 10.1007/s003590050335

Cite this article as:
Kröger, R., Campbell, M., Fernald, R. et al. J Comp Physiol A (1999) 184: 361. doi:10.1007/s003590050335

Abstract

The focal length of the vertebrate eye is a function of wavelength, i.e. the eye suffers from longitudinal chromatic aberration. Chromatic defocus is a particularly severe problem in eyes with high light-gathering ability, since depth of field is small due to a pupillary opening that is large in relation to the focal length of the eye. Calculations show that in such eyes only a narrow spectral band of light can be in focus on the retina. For the major part of the visual spectrum, spatial resolution should be limited by the optics of the eye and far lower than the resolving power achievable by the retinal cone photoreceptor mosaic. To solve this problem, fishes with irises unresponsive to light have developed lenses with multiple focal lengths. Well-focused images are created at the wavelengths of maximum absorbance of all spectral cone types. Multifocal lenses also appear to be present in some terrestrial species. In eyes with mobile irises, multifocal lenses are correlated with pupil shapes that allow all zones of the lens, with different refractive powers, to participate in the imaging process, irrespective of the state of pupil constriction.

Key words Color vision Chromatic aberration Spherical aberration Depth of field Pupil shape 

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • R. H. H. Kröger
    • 1
  • M. C. W. Campbell
    • 2
  • R. D. Fernald
    • 3
  • H.-J. Wagner
    • 1
  1. 1.Anatomisches Institut, Eberhard-Karls-Universität Tübingen, Österbergstrasse 3, D-72074 Tübingen, Germany e-mail: kroeger@anatu.uni-tuebingen.de Tel.: +49-7071-2973022; Fax: +49-7071-294014DE
  2. 2.School of Optometry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1CA
  3. 3.Neuroscience Program and Department of Psychology, Stanford University, Stanford, CA 94305, USAUS

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