A FLUORESCENT VESICLE SYSTEM FOR THE MEASUREMENT OF BLOOD VELOCITY INTHE CHOROIDAL VESSELS

BACKGROUND AND OBJECTIVE: Evaluation of the pathophysiologic mechanism s involved in the choroidal circulation is difficult because of the pr esence of the retinal pigment epithelium. The authors have developed a technique for measuring blood velocity in individual choroidal vessel s using the scanning laser ophthalmoscope and intravenously injected i ndocyanine green encapsulated in multilamellar vesicles. In this repor t, the authors describe their attempts to measure choroidal blood velo city in three different regions of the choroid of the primate eye. MAT ERIALS AND METHODS: A video-to-digital processor was used to digitize the video images of the choroid of a monkey at a sample rate of 1/30 o f a second. The blood velocity in the selected choroidal vessel segmen ts was calculated by measuring the distance the liposome traveled in a given time. RESULTS: The average blood velocities were 5.16 mm/s unde r the macula, 4.04 mm/s in the vortex vein system, and 2.03 mm/s in th e choroidal circulation nasal to the optic nerve. CONCLUSION: This tec hnique is an effective method of measuring blood velocity in a primate model and has several important advantages compared with the dye dilu tion technique.