Mild Hypoxia and Visual Performance with Night Vision Goggles
AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
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Pilots have frequently reported an apparent darkening of the visual field while flying at high altitude without supplemental oxygen, and subsequent exposure to oxygen resulted in marked increases in the brightness of lights. Likewise, at low light intensities visual acuity is greatly decreased during oxygen deprivation. In contrast, at high light intensities, the effect of moderate oxygen deprivation on visual acuity is slight. Even though the Night Vision Goggles NVGs amplify low night illumination, the interaction between amplified illumination and high altitude effects may prove to be important factors in visual performance. The objective of this research was to investigate the effects of mild hypoxia on monocular visual performance with NVGs. This study revealed that mild oxygen deprivation significantly affects unaided square-wave grating visual acuity but does not significantly affect NVG-augmented performance. Large differences between visual sensitivities at different spatial frequencies were not differentially affected by mild hypoxia. Supplemental oxygen did significantly improve naked-eye but not NVG-augmented night resolution acuity up to an altitude of 13,000 feet 3,692 m above sea level ASL.
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