Abstract

A test of visual contrast discrimination has been developed for demonstrating visual impairment due to anoxia at altitudes of 15,000 feet or above. It is made of photographically printed Landolt rings only slightly darker than their white background, and varying in contrast so as to cover the range just barely discriminated by different individuals at sea level and at altitude. Since moderate anoxia has little effect on vision in daylight, but causes a deterioration in contrast discrimination at twilight and night, the tests are designed to be viewed at a twilight brightness of about 0.1 millilambert. Trials with aviation cadets and other untrained persons have shown that the tests fulfill their purpose of demonstrating the effect of anoxia on vision. They also show the existence of large individual differences in the score at sea level and in the effect of altitude. The tests have been used in researches with skilled subjects on the effects of various procedures for producing anoxia, and have successfully given a quantitative measure of the resulting visual impairment.

© 1949 Optical Society of America

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References

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  1. R. A. McFarland and J. N. Evans, Am. J. Physiol. 127, 37 (1939).
  2. Wald, Harper, Goodman, and Krieger, J. Gen. Physiol. 25, 891 (1942).
  3. R. A. McFarland and M. H. Halperin, J. Gen. Physiol. 23, 613 (1940).
  4. McFarland, Halperin, and Niven, Am J. Physiol. 142, 328 (1944).
  5. Hecht, Hendley, Frank, and Haig, J. Gen Physiol. 29, 335 (1946).
  6. Hecht, Hendley, Shlaer, and Frank, (Committee on Medical Research, Washington, 1944).
  7. A. Chapanis, J. Aviation Med. 17, 348 (1946).
  8. Otis, Rahn, Epstein, and Fenn, Am. J. Physiol. 146, 207 (1946).
  9. Barach, Fenn, Ferris, and Schmidt, J. Aviation Med. 18, 73 (1947).
  10. A. L. Barach and et al., J. Aviation Med. 18, 252 (1947).

1947 (2)

Barach, Fenn, Ferris, and Schmidt, J. Aviation Med. 18, 73 (1947).

A. L. Barach and et al., J. Aviation Med. 18, 252 (1947).

1946 (3)

Hecht, Hendley, Frank, and Haig, J. Gen Physiol. 29, 335 (1946).

A. Chapanis, J. Aviation Med. 17, 348 (1946).

Otis, Rahn, Epstein, and Fenn, Am. J. Physiol. 146, 207 (1946).

1944 (1)

McFarland, Halperin, and Niven, Am J. Physiol. 142, 328 (1944).

1942 (1)

Wald, Harper, Goodman, and Krieger, J. Gen. Physiol. 25, 891 (1942).

1940 (1)

R. A. McFarland and M. H. Halperin, J. Gen. Physiol. 23, 613 (1940).

1939 (1)

R. A. McFarland and J. N. Evans, Am. J. Physiol. 127, 37 (1939).

Barach,

Barach, Fenn, Ferris, and Schmidt, J. Aviation Med. 18, 73 (1947).

Barach, A. L.

A. L. Barach and et al., J. Aviation Med. 18, 252 (1947).

Chapanis, A.

A. Chapanis, J. Aviation Med. 17, 348 (1946).

Epstein,

Otis, Rahn, Epstein, and Fenn, Am. J. Physiol. 146, 207 (1946).

Evans, J. N.

R. A. McFarland and J. N. Evans, Am. J. Physiol. 127, 37 (1939).

Fenn,

Barach, Fenn, Ferris, and Schmidt, J. Aviation Med. 18, 73 (1947).

Otis, Rahn, Epstein, and Fenn, Am. J. Physiol. 146, 207 (1946).

Ferris,

Barach, Fenn, Ferris, and Schmidt, J. Aviation Med. 18, 73 (1947).

Frank,

Hecht, Hendley, Frank, and Haig, J. Gen Physiol. 29, 335 (1946).

Hecht, Hendley, Shlaer, and Frank, (Committee on Medical Research, Washington, 1944).

Goodman,

Wald, Harper, Goodman, and Krieger, J. Gen. Physiol. 25, 891 (1942).

Haig,

Hecht, Hendley, Frank, and Haig, J. Gen Physiol. 29, 335 (1946).

Halperin,

McFarland, Halperin, and Niven, Am J. Physiol. 142, 328 (1944).

Halperin, M. H.

R. A. McFarland and M. H. Halperin, J. Gen. Physiol. 23, 613 (1940).

Harper,

Wald, Harper, Goodman, and Krieger, J. Gen. Physiol. 25, 891 (1942).

Hecht,

Hecht, Hendley, Frank, and Haig, J. Gen Physiol. 29, 335 (1946).

Hecht, Hendley, Shlaer, and Frank, (Committee on Medical Research, Washington, 1944).

Hendley,

Hecht, Hendley, Frank, and Haig, J. Gen Physiol. 29, 335 (1946).

Hecht, Hendley, Shlaer, and Frank, (Committee on Medical Research, Washington, 1944).

Krieger,

Wald, Harper, Goodman, and Krieger, J. Gen. Physiol. 25, 891 (1942).

McFarland,

McFarland, Halperin, and Niven, Am J. Physiol. 142, 328 (1944).

McFarland, R. A.

R. A. McFarland and M. H. Halperin, J. Gen. Physiol. 23, 613 (1940).

R. A. McFarland and J. N. Evans, Am. J. Physiol. 127, 37 (1939).

Niven,

McFarland, Halperin, and Niven, Am J. Physiol. 142, 328 (1944).

Otis,

Otis, Rahn, Epstein, and Fenn, Am. J. Physiol. 146, 207 (1946).

Rahn,

Otis, Rahn, Epstein, and Fenn, Am. J. Physiol. 146, 207 (1946).

Schmidt,

Barach, Fenn, Ferris, and Schmidt, J. Aviation Med. 18, 73 (1947).

Shlaer,

Hecht, Hendley, Shlaer, and Frank, (Committee on Medical Research, Washington, 1944).

Wald,

Wald, Harper, Goodman, and Krieger, J. Gen. Physiol. 25, 891 (1942).

Am J. Physiol. (1)

McFarland, Halperin, and Niven, Am J. Physiol. 142, 328 (1944).

Am. J. Physiol. (2)

R. A. McFarland and J. N. Evans, Am. J. Physiol. 127, 37 (1939).

Otis, Rahn, Epstein, and Fenn, Am. J. Physiol. 146, 207 (1946).

J. Aviation Med. (3)

Barach, Fenn, Ferris, and Schmidt, J. Aviation Med. 18, 73 (1947).

A. L. Barach and et al., J. Aviation Med. 18, 252 (1947).

A. Chapanis, J. Aviation Med. 17, 348 (1946).

J. Gen Physiol. (1)

Hecht, Hendley, Frank, and Haig, J. Gen Physiol. 29, 335 (1946).

J. Gen. Physiol. (2)

Wald, Harper, Goodman, and Krieger, J. Gen. Physiol. 25, 891 (1942).

R. A. McFarland and M. H. Halperin, J. Gen. Physiol. 23, 613 (1940).

Other (1)

Hecht, Hendley, Shlaer, and Frank, (Committee on Medical Research, Washington, 1944).

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Figures (1)

F. 1
F. 1

Contrast discrimination test, Model II, top view. Only 2 of the 18 pairs of C’s and of the scoring circles are shown. The cover has been removed, but the dotted rectangles represent openings in the cover.