Choroidal blood flow measured with a new confocal compact laser Doppler flowmeter

A new instrument for the measurement of choroidal blood now in the fovea is presented. It is based on the laser Doppler method and a confocal optical system with an indirect detection of the Doppler shifted light. Method The intensity of the laser beam (785 nm) at the cornea is 90 mu W. M easurements were obtained from a normal population of 21 subjects under res ting conditions without dilating the pupil. Results The reproducibility of the choroidal blood flow, based on 5 measure ments of 10 s each in 5 randomly selected subjects, is 9%. The minimum dete ctable change for a statistical significance of p less than or equal to 0.0 5, based on a population of 21 subjects and 10 s measurements, is 9%. Conclusion This new compact instrument appears to be suitable for the inves tigation of the physiology and pharmacology of choroidal blood now and the effect of age-related macular degeneration.