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.

隐形眼镜磨损是一种安全有效的校正形式，以折射误差。但是，由于慢性角膜水肿，许多人无法佩戴镜头。先前的研究表明，通过隐形眼镜诱导的缺氧产生的角膜水肿量存在显着的个体差异。我们将检验以下假设：角膜水肿的个体差异与角膜代谢活性的个体差异有关。在一大批普通受试者中，我们将测量角膜水肿，氧气消耗（QC）以及佩戴高氧透射性的隐形眼镜产生的酸负荷。角膜水肿将通过在三个小时的闭眼镜头磨损后测量角膜肿胀来确定。消耗将通过使用新的非侵入性技术来确定氧气张力（PO2）在已知的氧透射性的隐形眼镜下测量泪氧张力（PO2）。低氧酸负荷将通过测量闭合眼球透镜磨损期间角膜基质pH的变化来确定。我们的假设预测，对于给定的隐形眼镜，QC相对较高的个体将具有较低的泪液PO2（即相对较多的缺氧）。为了维持角膜能水平，这些个体应该对糖酵解代谢有更大的依赖，这将导致乳酸的产生更大。因此，该假设还预测，QC较高的个体将显示角膜pH值最大的下降。由于乳酸是缺氧角膜肿胀的渗透剂，因此这些人会显示出更大的角膜肿胀。另一种假设是，角膜肿胀的变异性是内皮功能变异性的函数，也将被测试。如果接受了主要的假设，则将开始进一步的研究，以确定较高代谢需求的个体在佩戴隐形眼镜时是否具有更大的倾向于发展临床并发症的倾向。如果是这样，这可能会导致基于快速，简单的角膜氧的量子，开发了与隐形眼镜磨损适用性的挑衅性测试。