高空缺氧環境下配戴各式隱形眼鏡之觀察

Changes Experienced by Users of Different Contact Lenses at Simulated Hypoxic Altitudes

劉峻正(Chun-Cheng Liu) ； 蔡明霖(Ming-Ling Tsai) ； 陳建同(Jiann-Torng Chen) ； 項正川(Jeng-Chuan Shiang) ； 張雲翔(Yun-Hsiang Chang) ； 黃敬堯(Ching-Yao Huang) ； 徐文錦(Wen-Jin Hsu) ； 洪啟庭(Chi-Ting Horng)

《中華民國眼科醫學會雜誌》 48卷1期 (2009/03) Pp. 19-26

https://doi.org/10.30048/ACTASOS.200903.0003

摘要

目的：分析高空缺氧環境下，配戴各種隱形眼鏡之變化，並觀察暴露後之症狀。
材料：本文報告50位男性志願者，第一組30位配戴軟式隱形眼鏡（再依含水量75%、55%、38%等，再區分為A、B、C三小組）、第二組配戴PMMA片，第三組則配戴RGP片，每位受志願者之矯正視力為20/20。依序於低壓艙內，戴上氧氣面罩，逐漸抽離艙內空氣，模擬逐漸上升之缺氧環境。每上升5000呎即以裂隙燈觀察鏡片下之變化，同時記錄其視力，一直到25000呎為止。隨後以相反步驟加入氧氣，象徵返回地面並完成實驗，步出艙後立刻卸除隱形眼鏡，再一次觀察其角膜與結膜情形。
結果：在第一A組中發現在5000呎時，80%的案例出現氣泡（部份出現在角膜中央者其視力降至20/30）；第一B組(60%)在5000呎與第一C組(50%)在10000呎，出現鏡片下小氣泡。第二組PMMA片者，全部在20000呎於鏡片下角膜中央處出現明顯的大氣泡（視力降低至20/40）。第三組配戴RGP片，僅10%的受測者在10000呎出現鏡片旁小氣泡。另外卸下隱形眼鏡後發現因缺氧之故，所有志願者或多或少都有角、結膜病變。
結論：高空缺氧環境下配戴各類型隱形眼鏡，部份出現鏡片下氣泡，可能會影響視力與造成後續的角、結膜病變。但民航機因有座艙加壓的設備，使得發生鏡片下氣泡之比例減少。但是配戴隱型眼鏡執勤的軍機飛行員，因機種不同，是否因此而影響飛行安全，值得個別評估。

並列摘要

Purpose: To evaluate the changes experienced by contact lens users wearing different types of contact lenses during and after exposure at simulated hypoxic altitudes.
Methods: We studied the right eye of 50 male volunteers in a low-pressure chamber that simulated various altitudes. The subjects were divided into three groups. Group 1 comprised soft contact-lens users; Group 2, PMMA-lens users; and Group 3 RGP-lens users. Group 1 was further divided into three subgroups according to the water contents of the contact lenses (1A: 70%, 1B: 55%, 1C: 38%). Corrected visual acuity was also measured. The subjects were examined under slit-lamp after every 5000-foot change in elevation. Up to the height of 25000 ft, extra room-air was re-supplied step by step, and all the volunteers returned to the sea-level without incident. After exposure, we also examined the changes in conjunctiva and cornea. (Why use 'ft' and not 'm' for the distance measurement?)
Result: In Group 1A, air bubbles were present at the edge and central part of the lens at 5000 ft in 80% of the cases. In 60% of the cases in Group 1B and 50% of the cases in Group1C, small bubbles appeared at 5000 ft and 10000 ft, respectively. In the PMMA-lens group, all cases had large air bubbles found in the central portion of lens at 20000 ft, and BCVA decreased. In the RGP-lens group, only 10% of the cases had small bubbles that appeared at lens margin at 10000 ft. After exposure, conjunctival injection and punctate epithelial keratitis were found in all volunteers.
Conclusion: Air bubbles might be found under various types of contact lens at simulated hypoxic altitudes. Visual acuity worsened in some situations. After exposure, conjunctival and corneal changes were found due to hypoxia. In commercial aircraft, the percentage of air bubbles appearing under the lens may decrease due to cabin pressure. Military aircrews wearing contact lens are likely to experience air-bubbles formed under the lens when working at high altitude. This may result in future physiological and visual degradation.

並列關鍵字

Sub-contact lens bubble ； low pressure chamber