RT Journal Article
SR Electronic
T1 Reproducibility and sensitivity of scanning laser Doppler flowmetry during graded changes in Po
2
JF British Journal of Ophthalmology
JO Br J Ophthalmol
FD BMJ Publishing Group Ltd.
SP 360
OP 364
DO 10.1136/bjo.81.5.360
VO 81
IS 5
A1 Karin Strenn
A1 Rupert Menapace
A1 Georg Rainer
A1 Oliver Findl
A1 Michael Wolzt
A1 Leopold Schmetterer
YR 1997
UL http://bjo.bmj.com/content/81/5/360.abstract
AB AIMS/BACKGROUND Recently a commercially available scanning laser Doppler flowmeter has been produced, which provides two dimensional maps of the retinal perfusion. The aim of the present study was to investigate the reproducibility and the sensitivity of these measurements. METHODS 16 healthy subjects were randomised to inhale different gas mixtures of oxygen and nitrogen in a double blind crossover study. The following gas mixtures of oxygen and nitrogen were administered: 100% oxygen + 0% nitrogen, 80% oxygen + 20% nitrogen, 60% oxygen + 40% nitrogen, 40% oxygen + 60% nitrogen, 30% oxygen + 70% nitrogen, 20% oxygen + 80% nitrogen, 15% oxygen + 85% nitrogen, and 10% oxygen + 90% nitrogen. Retinal haemodynamic variables and systemic haemodynamics were measured during all inhalation periods. Recordings under resting conditions were performed three times to calculate intraclass coefficients. RESULTS In two subjects we did not obtain technically adequate results. A dose dependent change in retinal blood flow during graded oxygen breathing was observed (p < 0.001). During 100% oxygen breathing blood flow decrease was between 29% and 33%, whereas blood flow increase was between 28% and 33% during inhalation of 10% oxygen + 90% nitrogen. CONCLUSIONS Scanning laser Doppler flowmetry has an acceptable reproducibility and is appropriate for description of the effect of graded changes in Po 2 on retinal haemodynamics. The main problems with the system are the large zero offset, the fixation during retinal scanning, and the neglect of blood flow changes during the cardiac cycle.