97th DOG Annual Meeting 1999
VARIABILITY OF LASER DOPPLER FLOWMETRY MEASUREMENTS
T. Emschermann, A. S. Bernd, L. E. Pillunat
Purpose: Various studies with the scanning laser doppler flowmeter (HRF) and with the continuous laser doppler flowmeter (LDF) demonstrated a high amount of measurements variability. Aim of the study was to evaluate whether the observed variation is due to interindividual or intraindividual factors.
Methods: Relative optic nerve blood flow, velocity and volume were determined in 60 eyes of 60 healthy volunteers. All parameters were measured at three different sessions at two different locations of the optic disc. The measurements were undertaken with a scanning laser doppler flowmeter and with a continuous laser doppler flowmeter. For statistical analysis a regression analysis was used.
Results: Continuous laser doppler flowmetry demonstrated the highest variability at the parameter velocity (correlation between measurements r=0.42). The correlation between optic nerve blood flow measurements was r=0,73 and between volume measurements r=0,64. The Heidelberg Scanning laser flowmeter showed comparable results (velocity r=0,7; volume r=0,73; flow r=0,69). There was found no significant difference in one of the parameters between both instruments.
Conclusion: The results presented show that the variability of laser doppler flowmetry measurements is mostly due to interindividual scattering. Intraindividual variance seems to be in an acceptable order of magnitude. Therefore both machines seem to be suitable for longitudinal studies.
Universitäts-Augenklinik Eppendorf, Martinistr. 52, D-20246 Hamburg