CORNEAL METABOLIC ACTIVITY IN HUMANS

人类角膜代谢活动

• 批准号: 6084014
• 负责人: Joseph Aurelio Bonanno
• 金额: $ 21.14万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6084014
• 关键词: acid base balance; biological polymorphism; clinical research; contact lens; cornea edema; corneal endothelium; fluorescent dye /probe; glycolysis; human subject; hypoxia; medical complication; nonblood rheology; noninvasive diagnosis; oxygen consumption; oxygen tension; oxygen transport; statistics /biometry; tear

Contact lens wear is a safe and effective form of correction for refractive error. However, a significant number of people are unable to wear lenses because of chronic corneal edema. Previous studies have shown significant individual differences in the amount of corneal edema produced by contact lens-induced hypoxia. We will test the hypothesis that individual differences in corneal edema are associated with individual differences in metabolic activity of the cornea. In a large group of normal subjects we will measure corneal edema, oxygen consumption (Qc) and acid load produced by wearing contact lenses of high, medium and low oxygen transmissibility. Corneal edema will be determined by measuring corneal swelling following three hours of closed eye lens wear. Oxygen consumption will be determined by using a new non-invasive technique for measuring tear oxygen tension (PO2) under contact lenses of known oxygen transmissibility. Hypoxic acid load will be determined by measuring the change in corneal stromal pH during closed eye contact lens wear. Our hypothesis predicts that individuals with a relatively high Qc will have lower tear Po2 (i.e., relatively more hypoxia) for a given contact lens wearing condition. In order to maintain corneal energy levels, these individuals should have a greater dependence on glycolytic metabolism, which will lead to greater production of lactic acid. Thus, the hypothesis also predicts that individuals with high Qc will show the greatest drop in corneal pH. Since lactate is the osmotic agent for hypoxic corneal swelling, these individuals will show greater corneal swelling. An alternate hypothesis, that variability in corneal swelling is a function of the variability in endothelial function, will also be tested. If the primary hypothesis is accepted, then further studies will be initiated to determine if individuals with high metabolic demand have a greater propensity toward developing clinical complications while wearing contact lenses. If so, this could lead to the development of a provocative test for suitability of contact lens wear based on a quick and simple measure of corneal oxygen consumption.

佩戴隐形眼镜是矫正屈光不正的一种安全有效的方式。然而，相当多的人由于慢性角膜水肿而无法佩戴镜片。先前的研究表明，隐形眼镜引起的缺氧引起的角膜水肿程度存在显着的个体差异。我们将检验这样的假设：角膜水肿的个体差异与角膜代谢活动的个体差异相关。在一大群正常受试者中，我们将测量佩戴高、中、低透氧性隐形眼镜时产生的角膜水肿、耗氧量（Qc）和酸负荷。角膜水肿将通过佩戴闭眼镜片三小时后测量角膜肿胀情况来确定。耗氧量将通过使用一种新的非侵入性技术来测量已知氧气透过率的隐形眼镜下的泪氧张力（PO2）。通过测量闭眼隐形眼镜佩戴期间角膜基质 pH 值的变化来确定低氧负荷。我们的假设预测，对于给定的隐形眼镜佩戴条件，Qc 相对较高的个体的泪液 Po2 较低（即相对较多的缺氧）。为了维持角膜能量水平，这些人应该更加依赖糖酵解代谢，这将导致更多的乳酸产生。因此，该假设还预测 Qc 高的个体角膜 pH 值下降幅度最大。由于乳酸是缺氧角膜肿胀的渗透剂，这些人会表现出更大的角膜肿胀。还将测试另一种假设，即角膜肿胀的变异性是内皮功能变异性的函数。如果主要假设被接受，那么将启动进一步的研究，以确定代谢需求高的个体在佩戴隐形眼镜时是否更容易出现临床并发症。如果是这样，这可能会导致开发出一种基于快速、简单的角膜耗氧量测量的隐形眼镜佩戴适宜性测试。