Role of Accommodation and Developmental Aspects of Experimental Myopia in Chicks

  • J. Wallman
  • D. Rosenthal
  • J. I. Adams
  • J. N. Trachtman
  • L. Romagnano
Part of the Documenta Ophthalmologica Proceedings Series book series (DOPS, volume 28)

Abstract

We have previously shown that extreme axial myopia (often more than 40 D) could be produced by raising chicks with their field of view restricted to the frontal visual field.

Since animals raised with their vision restricted to the lateral visual field do not become myopic, it is the specific visual experience that is important. Since chicks use the frontal visual field for near vision and the lateral for distance vision, it is possible that the amount of near vision is the relevant variable.

We have now completed a series of developmental studies on this experimental myopia. The results can be summarized as follows: (1) The myopia can be reversed, in most subjects, by removing the visual field restriction. (2) This recovery process is extremely rapid for young animals, but much slower for older animals. (3) The experimental myopia develops very rapidly, being substantial at one week of age and maximal at two weeks. (4) The myopia shows some spontaneous reversal even with the visual field restrictors still in place. This result seems consistent with a hypothesis implicating accommodation in the etiology of myopia, since severely myopic animals would presumably have little need to accommodate, and thus the myopia would decrease. (6) Normal chicks have rather variable refractions at hatching. These change in the direction of emmetropia over approximately the same time period that the myopia develops in the experimental chicks.

Taken together, these studies argue that although this experimental myopia, and the recovery from it, can both occur over a substantial period of the animals development, the extent of susceptibility to both processes changes greatly as the animal develops. The similarity in the developmental time course of the refractive changes in normal and myopic chicks argues that the experimental myopia may be the result of the same developmental regulatory mechanisms that normally cause the eye to grow toward correct refraction.

Longitudinal studies of the anatomical changes associated with the experimental myopia and recovery from it are in progress.

Keywords

Formalin Refraction Myopia Hyperopia Cycloplegia 

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References

  1. Belkin, M., Yinon, U., Rose L. & Reisert, I.: Effect of visual environment on refractive error of cats. Documenta Ophthalmol. 42: 433 (1977).CrossRefGoogle Scholar
  2. Gundlach, R. H., Chard, R. & Skahen, J. R.: The mechanism of accommodation in pigeons. J. Comp. Psychol. 38: 27 (1945).CrossRefGoogle Scholar
  3. McKanna, J. A. & Casagrande, V. A.: Reduced lens development in lid-suture myopia. Exp. Eye Res. 26:715 (1978).PubMedCrossRefGoogle Scholar
  4. Nye, P. W.: On the functional differences between frontal and lateral visual fields of the pigeon. Vision Res. 13: 559 (1973).PubMedCrossRefGoogle Scholar
  5. Pilar, G., Landmesser, L. & Burstein, L.: Competition for survival among developing ciliary ganglion cells. J. Neurophysiol. 43: 233 (1980).PubMedGoogle Scholar
  6. Sherman, S. M., Norton, T. T. & Casagrande, V. A.: Myopia in the lid-sutured tree shrew (Tupaia glis). Brain Res. 124: 154 (1977).PubMedCrossRefGoogle Scholar
  7. Sivak, J. G., Bobier, W. R., & Levy, B.: The refractive significance of the nictitating membrane of the bird eye. J. Comp. Physiol. 125: 335 (1978).CrossRefGoogle Scholar
  8. Sorsby, A.: Biology of the eye as an optical system. In: Clinical Opthalmology, Vol. 1, Ed. T. D. Duane New York, Harper and Row (1976).Google Scholar
  9. Wallman, J., Adams, J. I. & Trachtman, J. N.: The eyes of young chickens grow toward emmetropia. Invest. Ophthalmol. Vis. Sci. 20: 557 (1981).PubMedGoogle Scholar
  10. Wallman, J., Türkei, J. & Trachtman, J.: Extreme myopia produced by modest change in early visual experience. Science. 201: 1249 (1978).PubMedCrossRefGoogle Scholar
  11. Wiesel, T. N. & Raviola, E.: Myopia and eye enlargement following neonatal lid fusion in monkeys. Nature. 266: 66 (1977).PubMedCrossRefGoogle Scholar
  12. Wilson, J. R. & Sherman, S. M.: Differential effects of early monocular deprivation on binocular and monocular segments of cat striate cortex. J. Neurophysiol. 40: 891 (1977).PubMedGoogle Scholar
  13. Yinon, U., Rose, L. & Shapiro, A.: Myopia in the eye of developing chicks following monocular and binocular lid closure. Vision Res. 20: 137 (1979).CrossRefGoogle Scholar
  14. Young, F. A.: The effect of restricted visual space on the primate eye. Am. J. Ophthalmol. 52: 799 (1961).PubMedGoogle Scholar

Copyright information

© Dr W. Junk Publishers, The Hague 1981

Authors and Affiliations

  • J. Wallman
    • 1
  • D. Rosenthal
    • 1
  • J. I. Adams
    • 1
  • J. N. Trachtman
    • 1
  • L. Romagnano
    • 1
  1. 1.Biology Department, City CollegeCity University of New YorkNew YorkUSA

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