Normal-Diseased Corneas NASA-NEI CLINICAL DLS DEVICE

位于眼睛前面的透明角膜不仅作为折射介质将光线聚焦到视网膜上帮助我们看东西，而且还充当了眼睛前面的主要屏障和结构。严重的角膜疾病会导致混浊和失明。眼角膜疾病和损伤是当今美国人去眼科诊所就诊的主要原因。这些疾病也是最令人痛苦的眼疾之一。角膜研究的两个重要领域是：1)探索和了解角膜透明的分子基础；2)分析角膜伤口愈合和炎症的分子性质。 我们开发了一种新的临床设备来了解晶状体中发生的分子变化，NASA-NEI动态光散射(DLS)设备，它在角膜中也可能有用。实验室研究表明，它在检测白内障最早发生的变化方面具有潜力。对晶状体的临床研究也显示出良好的测试重复性、对微小变化的敏感性以及非侵入性、活体DLS临床白内障系统的安全性。 我们最初在动物身上进行了实验室研究，以确定DLS设备是否也适用于研究角膜。我们发现，在正常状态下，它可以检测到角膜不同层/隔室的分子差异。此外，我们发现，在角膜损伤后，如激光光折变手术、化学损伤和擦伤后，DLS可以检测到使用裂隙灯生物显微镜等光学设备无法明显或检测到的变化。这表明DLS可以作为一种无创的在体设备来研究正常状态和疾病状态下的角膜，并了解角膜透明度的分子基础。 在这个试点项目中，我们研究了志愿者的正常角膜、手术后角膜和病变角膜。在初步测试中，已经确定DLS临床白内障装置不适合角膜。这是因为角膜和晶状体之间的厚度不同(人类角膜的厚度为0.5 mm，而人类晶状体的厚度为3-4 mm)，因此氦-霓虹灯光束的入射角度与APD光探测器的角度不正确。 因此，我们开发了一种新的NASA-NEI角膜DLS设备。我们的NASA合作者(工程师和物理学家)根据志愿者的测试，对DLS设备进行了几个阶段的修改，现在我们已经获得了良好的可重复测量的角膜。我们发现：首先，DLS设备检测到角膜、晶状体和玻璃体之间蛋白质组成的基本差异，并显示出来自角膜糖蛋白和胶原的明显信号。其次，在比较正常和病变的角膜时，正常的、糖尿病的和手术后(LASIK)的角膜在蛋白质组成上有明显的差异。在正常角膜中，有两组蛋白质，一组直径为1000 nm，另一组直径为5000 nm。LASIK术后角膜在1000 nm处有一个峰，但第二个峰(较大的分子量)在8000 nm处。在糖尿病患者中，低分子量组大小在200到1000 nm之间(分布范围更广)，而大分子量蛋白质分布在2000到25000 nm之间(分布范围更广)。所有这些都是容易和安全的，体内(临床)，客观和非侵入性的。这些发现表明，这种新的DLS临床角膜装置可能在分子水平上检测和研究角膜异常。特别是，它可能有助于检测LASIK手术后的角膜变化，以及糖尿病和其他疾病。

The transparent cornea, located in the front of the eye, acts not only as a refracting medium to focus light on the retina and help us see, but also serves as the main barrier and structure in the front of the eye. Serious disease of the cornea leads to opacification and blindness. Corneal diseases and injuries are the leading reason for visits to eye care clinics in the U.S. today. These diseases are also some of the most painful eye disorders. Two important areas for research on the cornea are: 1) to explore and understand the molecular basis of corneal transparency, and 2) to analyse the molecular nature of corneal wound healing and inflammation. We developed a new clinical device to understand molecular changes that occur in the lens, the NASA-NEI Dynamic Light Scattering (DLS) device, which could also be useful in the Cornea. Laboratory studies have shown its potential in the detection of the earliest changes occuring in cataracts. Clinical studies on the lens have also shown good test-retest reproducibility, sensitivity to pick up small changes, and safety of the non-invasive, in vivo DLS clinical cataract system. We initially conducted laboratory studies in animals to determine if the DLS device is also useful to study the cornea. We found that it can detect molecular differences in various layers/compartments of the cornea in the normal state. In addition, we found that after corneal injury such as after laser photorefractive surgery, chemical injury and scraping, the DLS could detect changes which are not apparent or detectable using optical devices such as the slit lamp biomicroscope. This suggest that the DLS may be useful as a non-invasive, in vivo device to study the cornea in the normal state as well as in diseased states and to understand the molecular basis of corneal transparency. In this pilot project, we studied normal, post surgical and diseased corneas in volunteers. In preliminary testing, it was determined that the DLS clinical cataract device is not properly suited for the cornea. This is because of the difference in thickness between the cornea and the lens (0.5 mm in the human cornea versus 3-4 mmm in the human lens), so that the angle of entry of the Helium Neon Light beam versus the angle of the APD light detector is not correct. Hence we developed a new NASA-NEI DLS device for the cornea. After a number of stages of DLS device modifications done by our NASA collaborators (engineers and physicists) based on tests on our volunteers, we have now obtained good repeatable corneal measurements. We found the following: First, the DLS device detected basic differences in protein composition between cornea, lens and vitreous, and showed distinct signals from corneal glycoproteins and collagen. Second, in comparing normal and diseased corneas, there were distinct differences in protein composition between normal, diabetic and post surgical (LASIK) corneas. In normal corneas, there are 2 protein groups, one in the 1000 nm diameter size and another in the 5000 nm size. In post LASIK corneas, there is a peak in the 1000 nm size but the second peak (larger molecular weight) is in the 8000 nm size area. In diabetics, the lower molecular weight group ranges from about 200 to 1000 nm size (wider spread) and the large molecular weight proteins are spread from 2000 to 25,000 nm size (much wider spread). These were all performed easily and safely, in vivo (clinically), objectively and non invasively. These findings suggest that this new DLS clinical corneal device may be useful in detecting and studying corneal abnormalities in the molecular level. In particular, it may be useful in detecting corneal changes after LASIK surgery as well as in diabetes and other disorders.