Effects of Extended Hypoxia on Night Vision
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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The effects of sixteen days of sustained hypoxia 4300m equivalent on the dark adaptation threshold function were studied. Twelve male subjects were measured periodically days 2,4,6,9,11,13,16 of exposure over a 20-min test period for both red and green stimuli using a new computerized dark adaptometer. Comparison with sea level performance showed negligible elevations of thresholds for red response, but highly significant impairment of green response P00001 over almost the entire dark adaptation function. These losses peaked between the sixth and ninth day followed by little recovery, except at the eleventh day when the subjects descended briefly to 3200m elevation. Impairments developed rapidly again upon return to the original higher altitude. The results differ from previous published findings based on shorted exposure periods which showed only slight impairments of the early segment of dark adaptation. Implications of the results are discussed.
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