Pilot Sudy on Normal and Diseased Corneas with the NASA-

透明角膜位于眼睛前部，不仅作为折射介质将光线聚焦在视网膜上并帮助我们看到，而且还作为眼睛前部的主要屏障和结构。严重的角膜疾病可导致失明并伴有剧烈疼痛。角膜疾病和损伤是当今美国眼科诊所就诊的主要原因。角膜研究的两个重要领域是：1）探索和理解角膜透明度的分子基础，2）分析角膜伤口愈合和炎症的分子本质。 我们以前开发了一种新的临床设备，以了解发生在透镜中的分子变化，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。对透镜的临床研究也显示了良好的再现性、拾取微小变化的灵敏度以及非侵入性体内DLS临床白内障系统的安全性。 我们最初在动物中进行实验室研究，以确定DLS实验室探头/设备是否也可用于研究角膜。我们发现DLS实验室探针可以检测正常状态下角膜各层/隔室中的分子差异。此外，我们发现，角膜损伤后，如激光屈光手术，化学损伤和刮伤后，DLS可以检测到的变化是不明显的或使用光学设备，如裂隙灯生物显微镜检测。这表明，DLS可能是有用的，作为一种非侵入性的，在体内的设备，以研究角膜在正常状态以及在患病状态，并了解角膜透明度的分子基础。 在该试点项目中，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博士合作，并根据NASA-NEI机构间协议，基于与白内障器械相同的平台，创建了一种新的NASA-NEI DLS角膜临床器械（在来自意大利的具有三维瞄准系统的Keratron角膜标测系统和NASA航天飞机DLS探测器上）。在我们的NASA合作者（工程师和物理学家）基于对志愿者的试错测试进行了多个阶段的DLS设备修改后，我们现在已经获得了良好的可重复角膜测量。因此，我们检查了30名志愿者，并在仔细的裂隙灯检查和测试后招募了正常和异常角膜的患者。根据NEI-IRB批准的方案的要求，所有患者均提供了完全知情同意书并接受了全面的眼部检查。然后，他们接受了DLS测试，这需要10-15分钟后，眼睛检查。 我们发现了以下有趣的发现：首先，DLS临床设备检测到角膜，透镜和玻璃体之间的蛋白质组成的基本差异，并显示出来自角膜糖蛋白和胶原蛋白的不同信号。其次，在比较正常和患病角膜时，正常、糖尿病和手术后（LASIK）角膜之间的蛋白质组成存在明显差异。在正常角膜中，有2个蛋白质组，一个直径为1000 nm，另一个直径为5000 nm。在LASIK后角膜中，在1000 nm尺寸中存在峰，但第二峰（较大分子量）在8000 nm尺寸区域中。在糖尿病患者中，较低分子量组的范围为约200至1000 nm大小（更宽的范围），而大分子量蛋白质的范围为2000至25，000 nm大小（更宽的范围）。 这些都是容易和安全地进行，在体内（临床），客观和非侵入性。这些发现表明，这种新的DLS临床角膜装置可能是有用的检测和研究角膜异常的分子水平。特别是，它可以用于检测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睛中区分LASIK治疗的角膜和非LASIK治疗的角膜，此时很难通过临床手段彼此区分，这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.