Can the Response of the Iris to Light be Used to Break the Code of the Second Cranial Nerve in Man?

  • M. Alpern
  • N. Ohba
  • L. Birndorf


The sphincture muscle of the vertebrate iris develops tension causing the aperture stop of the eye to become small in the light, and loses tension making it expand in the dark. In this way, the light available to the sensory retina can alternatively be diminished when the world is too bright and increased when it is too dim. This elegant servomechanism is a textbook example, so we are told, of a homeostatic mechanism maintaining the exquisite sensitivity of the vertebrate retina constant while environmental light fluctuates. Nonsense! The maintenance of good retinal sensitivity over a range of 10,000,000,000,000 fold from the one extreme near the theoretical limit of detection to the other extreme at which the light becomes so intense that the retina starts to burn, is no doubt a prize achievement of Mother Nature as a bioengineer, but the photopupillary response has precious little to do with it. The small fluctuations of pupil area available (about 1.2 log10 units, for example, for the human eye) is trivial in this context.


Pupil Size Pupil Diameter Visual Pigment Pupil Response Aperture Stop 
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  1. Adrian, W. K. Proceedings of ARVO, 1971.Google Scholar
  2. Aguilar, M. and Stiles, W. A. Saturation of the rod mechanism of the retina at high levels of stimulation. Optica Acta, 1954, 1, 59–65.CrossRefGoogle Scholar
  3. Alexandridis, E. and Dodt, E. Pupillenlichtreflexe und pupillenweite einer stabchenmonochromatin. Albrecht Von Graefis Archiv Fuer Klinische Und Experimentelle Ophthalmologie, 1967, 173, 153–161.CrossRefGoogle Scholar
  4. Alpern, M. and Benson, D. J. Directional sensitivity of the pupillomotor photoreceptors. American Journal of Optometry, 1953, 30, 569–580.CrossRefGoogle Scholar
  5. Alpern, M. and Campbell, F. W. The spectral sensitivity of the consensual light reflex. Journal of Physiology, 1962, 164, 478–507(a).PubMedCentralPubMedGoogle Scholar
  6. Alpern, M. and Campbell, F. W. The behavior of the pupil during dark-adaptation. Journal of Physiology, 1962, 165, 5–7P(b).Google Scholar
  7. Alpern, M., Falls, H. F. and Lee, G. B. The enigma of typical total monochromacy. American Journal of Ophthalmology, 1960, 50, 996–1011.PubMedGoogle Scholar
  8. Alpern, M., Holland, M. G. and Ohba, N. Rhodopsin bleaching signals in essential night blindness. Journal of Physiology, 1972, 225, 457–476.PubMedCentralPubMedGoogle Scholar
  9. Alpern, M. and Ohba, N. The effect of bleaching and background on pupil size. Vision Research, 1972, 12, 943–951.PubMedCrossRefGoogle Scholar
  10. Alpern, M., Rushton, W. A. H. and Torii, S. The attenuation of rod signals by backgrounds. Journal of Physiology, 1970, 206, 209–228.PubMedCentralPubMedGoogle Scholar
  11. Barlow, H. B. Dark adaptation: A new hypothesis. Vision Research, 1964, 4, 47–58.PubMedCrossRefGoogle Scholar
  12. Barr, L. and Alpern, M. Photosensitivity of the frog iris. Journal of General Physiology, 1963, 46, 1249–1265.PubMedCentralPubMedCrossRefGoogle Scholar
  13. Bito, L. Personal communication to M. Alpern, 1973.Google Scholar
  14. Bouma, H. “Receptive systems mediating certain light reactions of the pupil of the human eye.” Thesis, 1965, Eindhoven, The Netherlands.Google Scholar
  15. Campbell, F. W. and Gregory, A. H. Effect of size of pupil on visual acuity. Nature, 1960, 187, 1121–1123.PubMedCrossRefGoogle Scholar
  16. Denton, E. J. The responses of the pupil of gekko gekko to external light stimulus. Journal of General Physiology, 1956, 40, 201–216.PubMedCentralPubMedCrossRefGoogle Scholar
  17. Fain, G. L. and Bowling, J. E. Intracellular recordings from single rods and cones in the mudpuppy retina. Science, 1973, 180, 1178–1181.PubMedCrossRefGoogle Scholar
  18. Falls, H. F., Wolter, J. R. and Alpern, M. Typical total monochromacy. Archives of Ophthalmology, 1965, 74, 610–616.PubMedCrossRefGoogle Scholar
  19. Geldard, F. A. The description of a case of total color blindness. Journal of the Optical Society of America, 1933, 23, 256–260.CrossRefGoogle Scholar
  20. Geldard, F. A. The Human Senses (2nd ed.) New York: John Wiley and Sons, 1973, p. 110.Google Scholar
  21. Green, D. G. and Maaseidvaag, F. Closed-circuit television pupillometer. Journal of the Optical Society of America, 1967, 57, 830–833.PubMedCrossRefGoogle Scholar
  22. Hagins, W. A. The visual process: Excitatory mechanisms in the primary receptor cells. Annual Review of Biophysics and Bioengineering, 1972, 1, 131–158.PubMedCrossRefGoogle Scholar
  23. Kuwabara, T. and Gorn, R. A. Retinal damage by visible light. Archives of Ophthalmology, 1968, 79, 69–78.PubMedCrossRefGoogle Scholar
  24. Noell, W. K. and Albrecht, R. Irreversible effects of visible light on the retina: Role of vitamin A. Science, 1971, 172, 76–80.PubMedCrossRefGoogle Scholar
  25. Norman, R. A. and Werblin, F. S. Proceedings of ARTO, 1973, p. 98.Google Scholar
  26. Rushton, W. A. H. The rod dark adaptation curve measured above cone threshold. Journal of Physiology, 1965, 181, 641–644(a).PubMedCentralPubMedGoogle Scholar
  27. Rushton, W. A. H. The ferrier lecture: Visual adaptation. Proceeding, Royal Society, Series B: Biological Sciences, London, 1965, 162, 20–46(b).CrossRefGoogle Scholar
  28. Spring, K. H. and Stiles, W. S. Variation of pupil size with change in the angles at which the light stimulus strikes the retina. British Journal of Ophthalmology, 1948, 32, 340.PubMedCentralPubMedCrossRefGoogle Scholar
  29. ten Doesschate, J. and Alpern, M. Effects of photoexcitation of the two retinas on pupil size. Journal of Neurophysiology, 1967, 30, 564.Google Scholar
  30. Wagman, I. H. and Gullberg, J. E. The relationship between monochromatic light and pupil diameter: The low intensity visibility curve as measured by pupillary measurements. American Journal of Physiology, 1942, 137, 769–778.Google Scholar
  31. Wald, G. The photochemistry of vision. Documenta Ophthalmologica, 1949, 3, 94.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1974

Authors and Affiliations

  • M. Alpern
    • 1
  • N. Ohba
    • 1
  • L. Birndorf
    • 1
  1. 1.Vision Research LaboratoryUniversity of MichiganAnn ArborUSA

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