Optical EngineeringChoroidal blood flow by laser Doppler flowmetry
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A method is described that provides measurements of blood flow (ChBF) in discrete regions of the choroidal vascular system. It is based on the technique of laser Doppler flowmetry (LDF). A diode laser beam (wavelength = 810 nm, 60 μW at the cornea) is delivered to the eye through a fundus camera. Light scattered by red blood cells in the tissue volume illuminated by the incident laser beam is detected at the fundus image plane of the camera by an optical fiber. Two analysis schemes of the Doppler signal are developed: one uses commercial skin blood flowmeters and the other a NeXTstation (Motorola 68040 based) computer system. Responses of ChBF to various stimuli are in good agreement with previously published findings in animals. LDF is a valid technique for obtaining noninvasive, continuous, and sensitive recordings of ChBF at discrete regions of the cat eye and in the foveal region of the human fundus, without the need to dilate the pupil.