Visual Fields During Acute Exposure to a Simulated Altitude of 7620 m
Authors: Horng, Chi-Ting; Liu, Chun-Cheng; Wu, Der-Min; Wu, Yi-Chang; Chen, Jiann-Torng; Chang, Cheng-Jong; Tsai, Ming-Ling
Source: Aviation, Space, and Environmental Medicine, Volume 79, Number 7, July 2008 , pp. 666-669(4)
Publisher: Aerospace Medical Association
Abstract:Horng C-T, Liu C-C, Wu D-M, Wu Y-C, Chen J-T, Chang C-J, Tsai M-L. Visual fields during acute exposure to a simulated altitude of 7620 m. Aviat Space Environ Med 2008; 79:666-9.Background: The hypoxia associated with sudden exposure to high altitude is known to impair vision and may thereby affect flight safety. However, no data were available regarding hypoxic effects on visual fields. The aim of this study was to evaluate black-and-white visual field sensitivity with acute hypoxia during acute exposure to a simulated altitude of 7620 m. Methods: Subjects were 15 male pilots 26-39 yr of age. We measured arterial oxygen saturation (Sao2%) using transdermal pulse oximetry while the visual field was measured within a 30° eccentricity in the right eye by computerized perimetry. The subject breathed 100% O2 for 30 min before and during chamber ascent, then removed his mask while measurements were performed. Results: The Sao2% and visual field sensitivities (mean ± SD) at ground level were 99.1 ± 0.4% and 43.9 ± 2.1 dB, respectively. During hypoxia, the Sao2% dropped to 64.0 ± 5.4% within 3 min. Mean visual sensitivity was significantly reduced by 7.2 ± 1.6 dB. Furthermore, peripheral sensitivity was slightly but significantly more diminished than central sensitivity. Conclusions: Severe acute hypoxia reduces central and moderate peripheral black-and-white vision by a factor of two with the strongest effect in the periphery.
Document Type: Research article
Publication date: 2008-07-01
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