Duijm H F, Rulo A H, Astin M, Mäepea O, van den Berg T J, Greve E L
Glaucoma Center (Department of Ophthalmology), University of Amsterdam, The Netherlands.
Exp Eye Res. 1996 Dec;63(6):693-704. doi: 10.1006/exer.1996.0163.
Choroidal hemodynamics estimated with parameters describing the dye build-up curves obtained with video fluorescein angiography, were compared with a classical regional blood flow measurement: radioactively labelled microspheres. Video fluorescein angiograms (Rodenstock's SLO 101) and microspheres blood flow measurements were made in 13 anaesthetized pigmented rabbits. Ocular perfusion pressures were varied from 60 to 15 mmHg by changing the intraocular pressure. The angiographically derived dye build-up curves were described by means of an exponential model. One of the model parameters is the time constant tau theoretically reflecting local blood refreshment time. Labelled microspheres act as a non-recirculating blood flow indicator, enabling the estimation of regional blood flows. The relation between choroidal blood flow and perfusion pressure is nearly linear, suggesting the passive nature of choroidal vasculature. There is a significant correlation between tau and microspheres flow (R = 0.67, P < 0.01). According to the rheological model the product of blood flow and tau corresponds to the relevant blood volume. Hence, a function for the volume of the choriocapillaris as a function of perfusion pressure was established. The model parameter tau can be interpreted as the local blood refreshment time. Since the parameter tau, unlike microspheres, can be used clinically, tau may be used to retrieve information on choroidal hemodynamics in clinical practice. Information on the spatial distribution of choroidal hemodynamics is also obtained.
通过视频荧光血管造影获得的描述染料蓄积曲线的参数来估计脉络膜血流动力学，并与经典的局部血流测量方法：放射性标记微球进行比较。在13只麻醉的有色家兔中进行了视频荧光血管造影（罗丹斯特克SLO 101）和微球血流测量。通过改变眼内压，使眼灌注压在60至15 mmHg之间变化。通过指数模型描述血管造影得出的染料蓄积曲线。该模型参数之一是时间常数tau，理论上反映局部血液更新时间。标记的微球作为非再循环血流指示剂，能够估计局部血流。脉络膜血流与灌注压之间的关系几乎是线性的，表明脉络膜血管系统的被动性质。tau与微球血流之间存在显著相关性（R = 0.67，P < 0.01）。根据流变学模型，血流与tau的乘积对应于相关血容量。因此，建立了脉络膜毛细血管体积作为灌注压函数的函数关系。模型参数tau可解释为局部血液更新时间。由于参数tau与微球不同，可用于临床，因此tau可用于在临床实践中获取有关脉络膜血流动力学的信息。还获得了有关脉络膜血流动力学空间分布的信息。
