A compact instrument is described that allows the measurement of the laser
Doppler flow parameters, i.e., the velocity, the volume, and flow of blood
in the foveal region of the human choroidal vascular system. This new devic
e uses the optical principle of confocality for the delivery of the laser l
ight to the site of measurement and heterodyne detection of the Doppler fre
quency shifted scattered light. Power of the incident light (785 nm) at the
cornea is 90 mu W. Measurements were obtained in both eyes of a group of 2
1 normal volunteers without pupil dilatation. We determined the intrasubjec
t reproducibility and the minimum statistically significant detectable chan
ges in the flow parameters for a group of 21 eyes (one in each subject). Li
near correlations were also established between the flow parameters in the
right and left eyes. (C) 1999 Society of Photo-Optical Instrumentation Engi
neers. [S1083-3668(99)00704-2].