Significance: The development of a technique allowing for non-invasive measurement of retinal blood flow (RBF) in humans is needed to understand many retinal vascular diseases (pathophysiology) and evaluate treatment with potential improvement of blood flow. Aim: We developed and validated an absolute laser Doppler velocimeter (LDV) based on an adaptive optical fundus camera that provides simultaneously high-definition images of the fundus vessels and absolute maximal red blood cells (RBCs) velocity to calculate the absolute RBF. Approach: This new absolute LDV is combined with the adaptive optics (AO) fundus camera (rtx1, Imagine Eyes©, Orsay, France) outside its optical wavefront correction path. A 4-s recording includes 40 images, each synchronized with two Doppler shift power spectra. Image analysis provides a vessel diameter close to the probing beam, and the velocity of the RBCs in the vessels are extracted from the Doppler spectral analysis. A combination of these values gives an average of the absolute RBF. Results: An in vitro experiment consisting of latex microspheres flowing in water through a glass capillary to simulate a blood vessel and in vivo measurements on six healthy humans was done to assess the device. In the in vitro experiment, the calculated flow varied between 1.75 and 25.9 μL / min and was highly correlated (r2 = 0.995) with the flow imposed by a syringe pump. In the in vivo experiment, the error between the flow in the parent vessel and the sum of the flow in the daughter vessels was between −11 % and 36% (mean ± sd, 5.7 ± 18.5 % ). RBF in the main temporal retinal veins of healthy subjects varied between 0.9 and 13.2 μL / min. Conclusions: The AO LDV prototype allows for the real-time measurement of absolute RBF derived from the retinal vessel diameter and the maximum RBCs velocity in that vessel.

中文翻译：

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使用激光多普勒测速仪与自适应光学相结合的绝对视网膜血流计

意义：需要开发一种允许对人类视网膜血流 (RBF) 进行无创测量的技术，以了解许多视网膜血管疾病（病理生理学）并评估可能改善血流的治疗方法。目的：我们开发并验证了基于自适应光学眼底相机的绝对激光多普勒测速仪 (LDV)，该相机同时提供眼底血管和绝对最大红细胞 (RBC) 速度的高清图像，以计算绝对 RBF。方法：这种新的绝对 LDV 与其光学波前校正路径外的自适应光学 (AO) 眼底相机（rtx1，Imagine Eyes©，Orsay，法国）相结合。4 秒记录包括 40 个图像，每个图像与两个多普勒频移功率谱同步。图像分析提供接近探测光束的血管直径，血管中红细胞的速度是从多普勒频谱分析中提取的。这些值的组合给出了绝对 RBF 的平均值。结果：一项体外实验由乳胶微球体在水中通过玻璃毛细管流动以模拟血管，并对六名健康人进行体内测量以评估该装置。在体外实验中，计算出的流量在 1.75 到 25.9 μL/min 之间变化，并且与注射泵施加的流量高度相关 (r2 = 0.995)。在体内实验中，母血管中的流量与子血管中的流量总和之间的误差介于 -11% 和 36% 之间（平均值 ± sd，5.7 ± 18.5 %）。健康受试者主要颞部视网膜静脉中的 RBF 在 0.9 至 13.2 μL/min 之间变化。结论：AO LDV 原型允许实时测量从视网膜血管直径和该血管中的最大 RBC 速度得出的绝对 RBF。