File:Medical studies in aviation (1918) (14750393586).jpg

Identifier: 101501719.nlm.nih.gov
Title: Medical studies in aviation
Year: 1918 (1910s)
Authors: Henderson, Yandell, 1873-1944
Subjects: Altitude Sickness Decompression Sickness Anoxia
Publisher: Chicago : American Medical Association
Contributing Library: U.S. National Library of Medicine

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lopia, would certainly impairhis efficiency and could easily result in an accident. AU-shaped piece was cut out of the Prince rule to fitover the nose, and a 2 mm. black dot on a white back-ground was used as a test object for making this deter-mination. Readings were taken without low oxygentension effect and with low oxygen tension effect, andthe effect of the administration of oxygen was deter-mined. Readings were taken every two minutes andcharted. One hundred and forty-seven men withnormal eyes were examined on the Henderson rebreath-ing apparatus, of whom 50.3 per cent, showed decreasein convergence power, 17.6 per cent, increase, 11.5 percent, fluctuation, and 20.6 per cent, no change. 57 Of eleven subnormal men examined (six were dis-qualified for visual acuity and live for muscularimbalance), 45.7 per cent, showed decrease in powerof convergence. Increased converging power, fluc-tuating changes and no change in the near point ofconvergence were each noted in 18.1 per cent. Of
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Fig. 4.—Contraction of field of vision in low-pressure chamber at pressures equivalent to 5,000,10,000, 15,000 and 20,000 feet. sixteen normal men examined in the low-pressurechamber, 50 per cent, showed falling off in power ofconvergence, none showed increase, fluctuating reac-tions were present in 12.5 per cent, and 37.5 per cent,remained unchanged. In the subnormal group therecession of the near point was very marked, some-times resulting in diplopia. 58 It was attempted to show what relationship, if any,exists between the convergence and the cardiovascularreactions to low oxygen tension. Seventy-two subjectsshowing an increase in pulse rate and a maintenancein pulse pressure gave these convergence changes,which would seem to indicate the ocular changes can-not be predicted by the cardiovascular reaction andvice versa: 54.2 per cent., decrease in power of con-vergence; 15.3 per cent., increase; 9.7 per cent., fluc-tuation, and 20.8 per cent., no change. The resultswould indicate

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