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T. Nagaoka, E. Sato, A. Takahashi, A. Yoshida; New System to Evaluate Wall Shear Stress on Retinal Vessel Using a Retinal Laser Doppler Velocimetry System . Invest. Ophthalmol. Vis. Sci. 2003;44(13):340.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To establish a system to evaluate wall shear stress on retinal vessels in humans. Methods: Eight healthy volunteers aged 19 to 23 participated in this study. The retinal vessel diameter (D) and mean blood velocity (Vm) were determined from both the retinal artery and vein using a retinal laser Doppler velocimetry system (Canon Laser Doppler Flowmeter; CLBF model 100). Retinal blood flow (RBF) and wall shear rate (WSR) were calculated by these two parameters. In addition, blood viscosity at the calculated shear rate was also measured in vitro at 37° C using a cone/plate viscometer. Wall shear stress on retinal vessels was calculated as the product of WSR and the blood viscosity. Results: The averaged values of the D, Vm, RBF, and WSR were, respectively, 116.1±17.5 m m, 35.2±9.4 mm/sec, 12.2±7.1 µL/min, and 1199±186 seconds-1 in the retinal artery and 145.9±12.2 µm, 23.8±3.3 mm/sec, 11.6±2.8 µL/min, and 627±88 seconds-1 in the vein. Blood viscosity values at the measured shear rate were 3.7±0.7 centi-Poise (cP) in the artery and 3.9±0.7 cP in the vein. Therefore, the averaged retinal wall shear rates were 44.7±11.6 dyne/cm2 in the artery and 24.7±6.6 dyne/cm2 in the vein. Conclusions: We demonstrated that the wall shear stress in retinal vessels can be measured in humans using the system that combines the CLBF and the viscometer. This system may be useful for further clinical investigation of the role of shear stress on the pathogenesis of various retinal disorders, such as diabetic retinopathy and retinal arteriosclerosis.
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