Developement of optical coherence tomography and its ophthalmologic application

为了获得眼前部的非侵入性高分辨率断层图像，我们建立了一台用于眼科应用的光学相干层析成像样机。这个装置是根据迈克尔逊的理论，使用低相干性红外光建造的。首先，我们研究了最适合该装置的光通、超发光二极管、分束器、反射镜等工程设置，最终获得了9微米以下的深度分辨率和100分贝以上的可检测水平。在对原型装置进行多次改进后，我们将其应用于猪角膜，获得了A-型图像。该仪器测量的角膜厚度与超声角膜测厚仪测量的角膜厚度具有较好的相关性。我们进一步从有或无上皮的中央角膜手动获得了精细的B超图像。因此，我们可以使用该设备区分磨损的角膜和正常的角膜。角膜-巩膜交界区的散射光由角膜向巩膜侧逐渐变化。因此，我们已经获得了几乎所有关于眼前段光学相干断层扫描的技术信息。因此，我们现在正计划制作第二代光学相干断层扫描，用于临床应用人类角膜和巩膜。

We established a prototype device of optical coherence tomography for ophthalmologic application in order to obtain noninvasively high-resolution tomographic images of anterior part of eyes. This device was built by the Michelson's theory using low-coherence infrared light. First, we investigated the most appropriate engineering set-up regarding light pass, super luminescent diode, beam-splitter, mirror etc., for this device, and finally achieved the depth resolution under 9 mum and the detectable level over 100 dB.After numerous improvements in the prototype device, we applied this to pig corneas to obtain A-mode images. A-mode images disclosed fine corneal structures, and the corneal thickness measured by this device was well correlated with that of ultrasonic pachometry. We further obtained fine B-mode images manually from central corneas with or without epithelium. Thus, we could differentiate abraded corneas from normal corneas using this device. The corneo-scleral junctional area showed a gradual change of scattering lights from corneal to scleral side. As a result, we have obtained almost all technical information regarding optical coherence tomography for the anterior segment of the eye. Therefore, we are now planning to make a second generation of optical coherence tomography for clinically applying human corneas and scleras.