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A. Wang, M. Yuan, M. J. Byrnes, A. Ingerman; Assessment of Choroidal Blood Flow Parameters Using Flom-S Laser Doppler Flowmeter: Reproducibility and Effect of Intense Light Exposure. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5038.
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The choroid plays an important role in supplying nutrients to and removing waste from the outer retina, including the fovea. Abnormal choroidal blood flow (ChBF) may therefore disrupt normal retinal function and lead to impairment of vision. Although Laser Doppler flowmetry (LDF) has recently been applied for the assessment of ChBF in humans, the marked variability of measurements obtained with this technology has precluded widespread use of this technique. In this study, we evaluated the reproducibility of LDF for ChBF parameters and assessed the effect of prolonged exposure to intense light on ChBF.
Confocal Laser Doppler flowmetry (LDF; HES-SO//Valais) was used to assess relative choroidal blood flow parameters - velocity (ChBvel), volume (ChBvol), and flow (ChBflow) - in the center of the fovea. The variability of LDF was assessed by taking multiple assessments of ChBF parameters in six subjects and calculating the coefficients of variation (CV). The effect of exposure to intense light (40,000 cd/m2 for 2 minutes) on ChBF was assessed in five normal subjects.
The following CV were observed for each parameter: ChBFvel = 5%, ChBFvol = 7% and ChBFflow = 8%. Variability of ChBF measurements was reduced with increased experience of the LDF operator as well as increased training of the subject. In addition, variability was also reduced by adjusting the LDF to maintain the same baseline DC value for each measurement. After a 2 minute exposure to intense light, minimal changes to ChBF parameters were observed (ChBFvol = 2%, ChBFve l= 1% and ChBFflow = 3%).
The CV in ChBF parameters (ChBFvel, ChBFvol, ChBFflow)observed in this study were 5%, 7% and 8%, respectively. These measurements represent a substantial improvement over previous reports (CV of 8%, 18%, and 13%, respectively). Our results indicate that appropriate training, standardization, and methodology, the reliability of ChBF assessment by confocal LDF can be substantially improved. With this method, , we found that a 2 minute exposure to intense light did not significantly affect ChBF.
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