ISSN:
1573-9686
Keywords:
Retinal vessels
;
Indocyanine green angiography
;
Shear rate
;
Hematocrit
;
Yield of fluorescence
;
Scanning laser
;
ophthalmoscope
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
,
Technology
Notes:
Abstract The purpose of this work was to obtain more quantitative knowledge about the yield of fluorescence from retinal vessles during indocyanine green angiography (ICG). The yield of fluorescence from blood was investigated for various shear rates, concentrations of ICG, and layer thicknesses. Measurements were performed in vitro on samples of human blood in a cone-plate shear chamber using frontal illumination as in scanning laser angiography. In blood and in plasma, the yield of fluorescence of ICG increased with concentration up to 0.05 and 0.1 mg/ml, respectively. At higher concentrations, the yield decreased for all layer thicknesses. For increasing layer thicknesses, both in plasma and in blood, the yield of ICG fluorescence increased nonlinearly for concentrations higher than 0.012 mg/ml. Saturation occurred for layers thicker than 200 μm in combination with ICG concentrations of 0.4 mg/ml and higher. Application of shear rates within the physiological range of the microcirculation (88/sec and 528/sec) increased the yield of fluorescence from the blood sample compared with stasis. The high transparency of blood for the excitation and emission light of ICG that was demonstrated will lead to superposition of fluorescence from superficial and deeper layers. This superposition precludes quantitative indocyanine angiography of ocular vessels.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00000014
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