25,000呎高空缺氧對視野的影響

The Effect of Altitude Hypoxia (25,000 ft) on Visual Field

洪啟庭(Chi-Ting Hong) ； 溫德生(Te-Sheng Wen) ； 劉峻正(Chun-Cheng Liu)

《中華民國航空醫學暨科學期刊》 20卷1期 (2006/06) Pp. 13-18

https://doi.org/10.7011/JAMSRC.200606.0013

摘要

人類的眼睛是對缺氧非常敏感的器官，當暴露於高空缺氧的環境，視覺的敏銳度、色覺和視野大小均會受到損害，其程度則隨壓力高度和暴露時間而變異。
本研究共有16位男性和4位女性參與，平均年齡為28.8歲，其裸眼視力皆在0.8（含）以上，具有低壓艙的經驗，他／她們先於海平面接受視野的測量，包括30°視野內4個象限隨機呈現的27個白色光點，測驗時間限為3分鐘；然後低壓艙上升至25,000呎，重覆前述的測驗，並比較各點的閾值。
本研究的結果發現在25,000呎模擬高空缺氮的時程，各光點的閾值皆顯著地較海平面為高（閾值為負），此顯示在3分鐘內視野的損害程度己及於趨近中央的區域，同時血氧飽和度已降低至61.9%。由於視力和視野均為飛行員狀態緊覺的重要資訊，故必須慎防急速減壓意外的發生。

關鍵字

高空缺氧 ； 視野 ； 低壓艙

並列摘要

Introduction. The eyes are the most sensitive organ to hypoxia. When exposing to high altitude, visual acuity, color vision, and visual field will be damaged to some extent. They vary with the ambient pressure and exposure time at that altitude. Methods. Sixteen male subjects and 4 female subjects gave consent and participated in this study. Their average age is 28.8 years with uncorrected visual acuity of at least 20/25. All of them have experienced altitude chamber flight previously. The visual field of the right eye of each subject was determined by static thresholds using an automated projection perimeter (Topcon SBP-3000). A customized test was used as identifying 27 points scattering over four quadrants within the visual field of 30°. Two trials were performed at sea level (control) and a simulated altitude of 25,000 ft respectively with a time Iimit of 3 minutes. Results. The analyzer showed that the mean threshold difference (dB) between normoxic and hypoxic condition was statistically significant (P＜0.001). It indicated that the damage of visual field had extended to the central area. Meanwhile, the blood oxygen saturation dropped to 61.9%. Conclusion. Because visual cues are the most important component for situational awareness, the pilot shall be alert against the risk of rapid decompression in flight.

並列關鍵字

altitude hypoxia ； visual field ； altitude chamber