Abstract

The state of focus of the eye in dim light and in total darkness was investigated by photographing the Purkinje images of a double aperture placed over a high speed flash lamp. Measurement of the photographed images showed that all subjects, when viewing a dim scene, remained focused for far vision. By subjective test, however, these subjects were myopic under the same conditions of dim light. The experimental results thus favor the theory that “night myopia” is a result of the aberrations of the eye and is not due to accommodation. The flash photographs taken in total darkness showed that three subjects remained focused for far vision; the fourth subject sometimes accommodated, by amounts varying between 0.5 and 1.5 diopter.

© 1953 Optical Society of America

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References

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  1. Koomen, Scolnik, and Tousey, J. Opt. Soc. Am. 41, 80 (1951).
    [Crossref]
  2. Hotchkiss, Washer, and Rosberry, J. Opt. Soc. Am. 41, 600 (1951).
    [Crossref]
  3. M. A. Bouman and G. van den Brink, Ophthalmologica 123, 100 (1952).
    [Crossref] [PubMed]
  4. J. M. Otero, J. Opt. Soc. Am. 41, 942 (1951).
    [Crossref] [PubMed]

1952 (1)

M. A. Bouman and G. van den Brink, Ophthalmologica 123, 100 (1952).
[Crossref] [PubMed]

1951 (3)

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Figures (4)

F. 1
F. 1

Apparatus for photographing the Purkinje images for various states of accommodation. A, flash lamp covered with a double aperture; B, camera; C, accommodation-fixing test object.

F. 2
F. 2

Photographs of Purkinje images of emmetrope R.S. under various conditions. In Fig. 2(A) the eye was focused for 5 meters (far vision), in 2(B) for 25 cm, and in 2(C) the eye was in total darkness.

F. 3
F. 3

Photographs of Purkinje images of emmetrope M.K., who had particularly diffuse images. In Fig. 3(A) the eye was focused for 5 meters (far vision), in 3(B) for 50 cm, and in 3(C) the eye was in total dakrness.

F. 4
F. 4

Separation of the second Purkinje images of a double aperture, plotted as a function of the state of accommodation. Graphs A and B are for nearly emmetropic subjects; C is for a low myope. To the right of each graph are plotted the image separations when the eye viewed a distant, dimly illuminated scene and when the eye was in complete darkness. In the two latter cases there was no attempt to fix the subject’s state of accommodation.