In Situ Analysis of Fundus Blood Flow - Real Time Measurements of Blood Vessel and System Development -

本研究的目的是建立一种真实的实时测量视网膜血管直径的光学方法，并结合激光视网膜血流计建立眼底血流原位分析系统。一些专题研究结果综述如下。利用眼底照相机、白色光源、光纤和多通道光谱仪构建了视网膜光谱反射率测量实验装置.从人类受试者测量的视网膜光谱反射率进行了分析，以确定光源的最佳波长为5 - 70 nm的高对比度血管成像。提出了一种基于颜色感知的动脉和静脉光学识别方法.利用线性图像传感器研制了一种视网膜血管直径测量装置。在该单元中，传感器的扫描时间设置为125毫秒，可以在传感器上25-50个像素的区域内对血管进行成像。4.为了成功地从线阵图像传感器的信号中确定血管直径，开发了一个新的信号处理软件，该软件采用像素数据的移动平均和微分.对测量单元进行校准测试。并将该方法与视频图像血管分析方法进行了比较，结果表明了该方法的有效性.将测量视网膜血管直径的装置与激光视网膜血流计相结合，并修改了一些软件程序，以真实的时间方式同时测量血流速度、血管直径和血流速率。最后，通过增加一些功能，建立了眼底血流的原位分析系统，本研究提出的颜色感知血管识别方法可能对血氧饱和度的测量有潜在的应用价值。

The purpose of this study is to develop an optical method for real time measurements of retinal vessel diameter and to establish the in situ analyzing system of fundus blood flow by combining with the laser retinal blood flowmeter. Some topical results are reviewed below.1. To measure the retinal spectral reflectance, an experimental apparatus was constructed by using a fundus camera, white light source, optical fiber, and multi-channel spectrometer.2. Analysis of the retinal spectral reflectance measured from human subjects was carried out to determine the optimum wavelength of the light source to be 5 70 nm for high-contrast imaging of vessels. A new method was proposed for optical discrimination of artery and vein using color perception.3. A unit for measuring retinal vessel diameters was developed by using a linear image sensor. In this unit, the scanning time of the sensor was set to be 125 msec and vessels may be imaged over a region of 25-50 pixels on the sensor.4. To determine successfully the vessel diameter from signals of the linear image sensor, a signal-processing software was newly developed by means of the moving average and differentiation of pixel data.5. A calibration test was conducted to the measuring unit. Then, this method was compared with the vessel analysis of video images, and results showed the usefulness of this method.6. The unit for measuring retinal vessel diameters was combined with the laser retinal blood flowmeter, and some software programs were modified to measure simultaneously the blood flow velocity, vessel diameter, and blood flow rate in a real time manner. Finally, the in situ analyzing system of fundus blood flow was established by installing some additional functions.The color perception method for vessel discrimination proposed in this study may potentially be useful for oxygen saturation measurements.