University of California, Berkeley and University of California, San Francisco, Joint Graduate Group in Bioengineering, Berkeley, California 94720-2020, USA.
Invest Ophthalmol Vis Sci. 2010 Mar;51(3):1691-8. doi: 10.1167/iovs.09-4483. Epub 2009 Nov 11.
To demonstrate a noninvasive method to visualize and analyze the parafoveal capillary network in humans.
An adaptive optics scanning laser ophthalmoscope was used to acquire high resolution retinal videos on human subjects. Video processing tools that enhance motion contrast were developed and applied to the videos to generate montages of parafoveal retinal capillaries. The capillary network and foveal avascular zone (FAZ) were extracted using video and image analysis algorithms. The capillary densities in the zone immediately outside the FAZ were calculated and the variation in density as a function of direction was investigated. Extracted FAZ geometries were used to calculate area and effective diameters. The authors also compared their method against fluorescein angiography (FA) for one subject.
The parafoveal capillaries were clearly visible when the motion contrast in noninvasive videos was enhanced. There was a marked improvement in the contrast of the parafoveal capillaries when compared to the unprocessed videos. The average FAZ area was 0.323 mm(2), with an average effective diameter of 633 microm. There was no variation in capillary density near the FAZ in different directions.
Using motion cues to enhance vessel contrast is a powerful tool for visualizing the capillary network, in the absence of contrast agents. The authors demonstrate a tool to study the microcirculation of healthy subjects noninvasively.
展示一种非侵入性的方法，以可视化和分析人类的旁中心毛细血管网络。
使用自适应光学扫描激光检眼镜在人体受试者身上获取高分辨率的视网膜视频。开发了增强运动对比度的视频处理工具，并将其应用于视频中，以生成旁中心视网膜毛细血管的蒙太奇。使用视频和图像分析算法提取毛细血管网络和中心无血管区（FAZ）。计算 FAZ 区域外的毛细血管密度，并研究密度随方向的变化。提取的 FAZ 几何形状用于计算面积和有效直径。作者还比较了他们的方法与一个受试者的荧光素血管造影（FA）。
当增强非侵入性视频中的运动对比度时，可以清楚地看到旁中心毛细血管。与未处理的视频相比，旁中心毛细血管的对比度有了显著提高。FAZ 的平均面积为 0.323 平方毫米，平均有效直径为 633 微米。在 FAZ 附近，不同方向的毛细血管密度没有变化。
使用运动线索来增强血管对比度是在没有造影剂的情况下可视化毛细血管网络的有力工具。作者展示了一种工具，可以非侵入性地研究健康受试者的微循环。
