Hypoxic effects on corneal morphology and function.
Hypoxic effects on corneal morphology and function.
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DOI：
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发表时间：
1990-08
影响因子：
4.4
通讯作者：
Kenneth A. Poise;Richard J. Brand;S. R. Cohen;Michel Guillon
中科院分区：
文献类型：
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作者：
Kenneth A. Poise;Richard J. Brand;S. R. Cohen;Michel Guillon
正常的角膜新陈代谢依赖于一个临界的氧气水平，低于这个水平就会发生一系列的急性角膜反应，包括基质乳酸的增加，细胞间pH的降低，以及角膜水化的增加。当恢复正常氧气时，这些急性反应是可逆的；然而，已有研究表明，长期暴露于低氧水平会导致角膜内皮细胞的永久性形态变化。临床医生担心，这些观察到的结构变化也可能伴随着角膜生理的变化。这种影响是否会发生尚不清楚，因为准确评估人类角膜功能一直是困难的。最近，我们开发了一种体内测试，能够测量整体角膜水化控制，可以用来研究低氧对角膜功能的影响。这项测试提供了有关水化控制的几个特征的信息，其中之一是诱导角膜肿胀后每小时角膜厚度恢复的百分比(PRPH)。在这项研究中，我们假设角膜缺氧同时伴随着长期配戴和聚甲基丙烯酸甲酯(PMMA)隐形眼镜，并且接受的剂量与过去配戴镜片的年份有关。使用这一范式，我们在36名不同配戴隐形眼镜史的受试者中，探索了低氧剂量与内皮细胞多染指数(EPI)、内皮细胞密度(ECD)和PRPH的关系。基于多元回归分析，发现与低氧剂量(调整年龄和性别)相关的相对变化(以百分比表示)具有剂量依赖性，相应的估计变化分别为1.70%/年、-0.25%/年和-1.26%/年，EPI、ECD和PRPH的95%可信限分别为(-0.3、3.7)、(-1.4、0.9)和(-2.6、0.06)。这些初步数据表明，低氧暴露改变了内皮细胞的形态并降低了角膜功能；然而，重要的是要指出，这是一项具有几个局限性的探索性研究，因此在更多确定的研究完成之前，这些结果应该被视为初步的。
Normal corneal metabolism depends on a critical level of oxygen, below which a series of acute corneal responses occur, including an increase in stromal lactate, a reduction in intercellular pH, and an increase in corneal hydration. These acute responses are reversible when normal oxygen is restored; however, it has been shown that chronic exposure to low oxygen levels can result in permanent morphologic changes in the corneal endothelium. Clinicians have expressed concern that these observed structural changes may also be accompanied by alterations in corneal physiology. Whether such effects occur is not known, since it has been difficult to assess human corneal function accurately. Recently, we have developed an in vivo test, able to measure overall corneal hydration control, that can be used to study the effects of hypoxia on corneal function. This test provides information on several characteristics of hydration control, one of which is the percent corneal thickness recovery per hour (PRPH) after inducing corneal swelling. In this study, we assumed that corneal hypoxia accompanies both extended and polymethylmethacrylate (PMMA) contact lens wear and that the dose received is related to the years of past lens wear. Using this paradigm, we explored the relationship of hypoxic dose to an endothelial polymegethism index (EPI), endothelial cell density (ECD), and PRPH in 36 subjects with varying contact lens wearing histories. Based on multiple regression analysis, the relative change (expressed as percent per year) associated with hypoxic dose (adjusted for age and gender) was found to be dose-dependent and corresponded to estimated changes of 1.70%/yr, -0.25%/yr, and -1.26%/yr, with 95% confidence limits of (-0.3, 3.7), (-1.4, 0.9), and (-2.6, 0.06) for EPI, ECD, and PRPH, respectively. These preliminary data suggest that hypoxic exposure alters endothelial morphology and reduces corneal function; however, it is important to indicate that this was a exploratory investigation with several limitations, and that therefore these results should be viewed as preliminary until more definitive studies are completed.