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M.H. Geiser, O. Savy, F. Küchler, P. Drillat, M. Tonini, M. Mouillon, J.–P. Romanet, C. Chiquet; Choroidal Blood Flow Of Patient Undergoing A Hemodilution For Treating Retinal Veins Occlusions . Invest. Ophthalmol. Vis. Sci. 2006;47(13):510.
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To evaluate the effect of hemodilution on sub–foveal choroidal blood flow (ChBF) in the human eye with retinal veins occlusion.
ChBF was measured by laser Doppler flowmetry (LDF) in 18 patients (54+/–13 mean+/–stdev, between 22 and 81 years old) with retinal vein occlusion (RVO) in one eye. LDF is based on the light scattered by the tissues and the red blood cells (RBCs); corresponding parameters are the velocity (ChBVel), the volume (ChBVol) and the flow (ChBF = ChBVel x ChBVol). Criterion to validate the measurements is the reproducibility of the amount of backscattered light (DC) from the fundus which is about three order of magnitude higher than the Doppler signal. Isovolemic hemodilution was performed in patients with RVO after informed consent, when hematocrit was higher than 35%. LDF parameters were measured on both eyes in two sessions: 1 hour before and 1 hour after the hemodilution.
33 hemodilutions were performed for the 18 patients. Hematocrit was lowered from 40% to 32%. Some patients missed one to three sessions of of measurements. Comparison between LDF parameters of each eye were done only when the amount of backscattered light did not vary for more than 20%. Change of LDF parameters after the hemodilution for healthy eye (16 hemodilutions) and for the eye affected by RVO (22 hemodilutions) are shown in table.
These preliminary results suggest that the reduction of hematocrit in patient with retinal vein occlusions after isovolemic hemodilution leads to vascular changes in the sub–foveal choroid. Because ChBVel did not changed, the decrease of ChBF in the affected eye could be explained by the decrease of hematocrit (i.e. the amount of scatters). Also not significant, the healthy eye exhibits an opposite change which suggests a probable modification of the scattering tissues.
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