In vivo measurement of ocular circulation with the Laser Speakle Method. Development of apparatus and application in ophthalmological research.

我们用激光散斑系统测量了在体人视网膜静脉的血流速度。我们还试图测量用于计算视网膜小静脉血流速度的归一化模糊（NB）值是否适用于椎间盘附近的视网膜静脉。然而，NB值有一个测量上限。我们研制了一种新的临床应用装置，并采用血流速度的定量指标--平方模糊率（SBR）来测量视盘附近的视网膜血流速度。该系统由红外CCD摄像机、监视显示系统、半导体激光器、图像传感器和高斑点微机组成。用二极管激光器通过眼底照相机照射包括目标视网膜静脉的眼底区域，并且将激光散斑图案成像到区域传感器上。从散斑图案的对比度的时间变化，使用逻辑板计算激光强度和偏差，并且还使用个人计算机计算SBR值。在体外实验中，从用作视网膜静脉的模拟物的玻璃毛细管中的血流获得的SBR与管的直径、实际血流速率和用作脉络膜循环的模拟物的背景SBR值相关。在活体实验中，根据离体实验的结果，用Monogram对16只正常人眼直径约为150 μm的视网膜静脉的血流速度进行了估算。视网膜静脉平均血流速度为18.4 ± 3.8mm/s（mean ± SD，n = 16）。2分钟间隔测量的重复性系数为3.6 ± 0.9%，一次测量时间为60 ± 11 s。

We have measured the in vivo blood velocity in human retinal veins using a laser speckle system. We also tried to measure whether the normalized blur (NB) value for calculating the retinal venule blood velocity was applicable to the retinal veins near the disc. The NB value, however, had an upper measurement limit. We have constructed a new apparatus for clinical application and also adopted the square blur rate (SBR), a quantitative index of blood velocity, for measuring retinal blood velocity near the disc This system consists of an infrared CCD camera, a monitor display system, a diode laser, an image sensor, and a high speck personal computer including Windows 98-based analyzing system. The funds area, including a target retinal vein, is illuminated with a diode laser through a fundus camera and the laser speckle pattern is imaged onto the area sensor. From the time change of the contrast of the speckle pattern, laser intensity and deviation are calculated using a logic board and the SBR value is also calculated using a personal computer. In an in vitro experiment the SBR obtained from blood flow in a glass capillary tube, used as an analogue of a retinal vein, was correlated with the diameter of the tube, the actual blood flow rate, and the background SBR value, which was used as an analogue of choroidal circulation. In the in vivo experiment the blood velocity in human retinal veins of approximately 150 μm in diameter was estimated in 16 normal human eyes using monograms based on the results of the in vitro experiment. Velocity averaged 18.4 ± 3.8mm/s (mean ± SD, n = 16) in retinal veins of 146 ± 6μm diameter. The coefficient of reproducibility of 2-minute interval measurements was 3.6 ± 0.9 %, and it took 60 ± 11s for one measurement The present methodology is clinically valid for measuring blood velocity in retinal veins.