Pilot Sudy on Normal and Diseased Corneas with the NASA-

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失明并伴有剧烈的疼痛。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。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。 我们之前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，即NASA-NEI动态光散射(DLS)设备。实验室研究表明，它在检测白内障最早发生的分子变化方面具有潜力。对晶状体的临床研究也表明，这种无创、活体DLS临床白内障系统具有良好的重复性、对微小变化的敏感度和安全性。 我们最初在动物身上进行了实验室研究，以确定DLS实验室探头/设备是否也适用于研究角膜。我们发现，在正常状态下，DLS实验室探针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，与来自俄亥俄州克利夫兰的NASA-John Glenn RC的物理学家Rafat Ansari和Kwang Suh博士以及NASA-NEI机构间协议合作，基于与白内障设备相同的平台(基于意大利的Keratron角膜测绘系统和NASA航天飞机DLS探测器)，为角膜创建了一种新的NASA-NEI DLS临床设备。美国宇航局的合作者(工程师和物理学家)根据对志愿者的试验和错误测试，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。因此，我们对30名志愿者进行了检查，并招募了角膜正常和异常的患者，经过仔细的裂隙灯检查和测试。所有患者都完全知情同意，并按照NEI-IRB批准的议定书的要求进行了全面的眼科检查。然后，他们接受了DLS测试，在眼睛检查后花了10-15分钟。 我们发现了以下有趣的发现：首先，DLS临床设备检测到角膜、晶状体和玻璃体之间的蛋白质组成基本不同，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手术后的角膜问题，以及糖尿病和其他疾病。它还将有助于解决其他问题，例如在为移植患者捐赠的眼库眼中区分接受LASIK治疗的和未接受LASIK治疗的角膜，这些眼球目前很难通过临床手段相互区分，对移植患者构成危险。

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 can lead to blindness accompanied by severe pain. Corneal diseases and injuries are the leading reason for visits to eye care clinics in the U.S. today. 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 previously developed a new clinical device to understand molecular changes that occur in the lens, the NASA-NEI Dynamic Light Scattering (DLS) device. Laboratory studies have shown its potential in the detection of the earliest molecular changes occuring in cataracts. Clinical studies on the lens have also shown good 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 laboratory probe/device is also useful to study the cornea. We found that the DLS lab probe 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, in collaboration with Drs. Rafat Ansari and Kwang Suh, physicists from NASA-John Glenn RC in Cleveland, Ohio, and undet the NASA-NEI Inter Agency Agreement, a new NASA-NEI DLS clinical device was created for the cornea, based on the same platform as the cataract device (on the Keratron Corneal Mapping System from Italy which has the 3 dimensional aiming system, and the NASA space shuttle DLS probe). After a number of stages of DLS device modifications done by our NASA collaborators (engineers and physicists) based on trial and error tests on our volunteers, we have now obtained good repeatable corneal measurements. We therefore examined 30 volunteers and recruited patients with normal as well as abnormal corneas after careful slit lamp examination and testing. All patients gave full informed consent and underwent comprehensive eye examinations, as required by the NEI-IRB approved Protocol. They then underwent DLS testing, which took 10-15 minutes after the eye examinations. We found the following intersting findings: First, the DLS clinical 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 problems after LASIK surgery as well as in diabetes and other disorders. It will also be useful in solving other problems, such as in differentiating between LASIK treated and non LASIK treated corneas among eye bank eyes donated for transplant patients, which at this time are very difficult to distinguish from each other by clinical means, posing a danger to transplanted patients.