FUJII Hitoshi Department of Computer Science and Electronics, Kyusyu Institute of Technology, professor, 情報工学部, 教授 (70133775)
NAGAHARA Miyuki Graduate School of Medicine Faculty University Hospital Sensory and Motor System Medicine, the University of Tokyo, assistant, 医学部・附属病院, 助手 (50262134)
|Budget Amount *help
¥24,900,000 (Direct Cost : ¥24,900,000)
Fiscal Year 1999 : ¥12,000,000 (Direct Cost : ¥12,000,000)
Fiscal Year 1998 : ¥12,900,000 (Direct Cost : ¥12,900,000)
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.