RETINAL BLOOD FLOW MEASUREMENT

可以使用激光触发的脂体包裹的荧光染料 就像眼睛里的追踪剂。荧光素在眼科中的广泛应用 诊断，但必须局部应用或注射 静脉注射，导致染料通过静脉扩散 视网膜循环与高水平背景 脉络膜中有荧光。羧基荧光素和钙黄素，染料 类似于荧光素，可以高密度地被包裹在脂质体中 浓度(100 Mm)。在浓度如此高的情况下， 荧光被猝灭，但当染料从 脂质体，稀释后发出强烈的荧光。脂质体 含有这些荧光染料的人可以静脉注射和 一旦进入循环，就可以被触发释放其内容 通过来自激光的局域光脉冲。染料转化为 激光加热，这会提高脂质体的温度 包膜，裂解脂质体，释放染料。一种能力 为了控制染料释放的位置、时间和重复， 允许在没有背景的情况下可视化局部流动模式 脉络膜下循环或邻近血管 网络。该系统将对局部灌注进行评估 可能存在缺陷。创造出更好定义的波前， 通过产生推进剂实现的，为 流量的定量测量。通过控制时间间隔 染料从脂质体中的释放量和时间 记录下来，我们已经能够在初步研究中测量 体外血流速度，以及视网膜血管中的血流速度 兔子和猴子。此外，可能会重复 过程允许改进对齐和聚焦 相机，从而优化照片的质量。 此外，还可以在测量之前和之后执行测量 引起生理条件(即氧气或氮气)的变化 呼吸、暴露于光线或药剂)。这个 系统提供对时间、位置和重复的控制 交付，这可能会在许多方面有用 治疗应用也是如此。

Laser-triggered, lipsome-encapsulated fluorescent dyes can be used as a tracer in the eye. Fluorescein is widely used in ophthalmic diagnosis, but it must be applied topically or injected intravenously, resulting in diffuse spread of dye through the retinal circulation along with high levels of background fluorescence in the choroid. Carboxyfluorescein and calcein, dyes similar to fluorescein, can be encapsulated in liposomes at high concentrations (100 mM). At such elevated concentrations, the fluorescence is quenched, but when the dye is released from the liposome, it is diluted and fluoresces intensely. Liposomes containing these fluorescent dyes can be injected intravenously and once in the circulation, can be trigged to release their contents by a localized pulse of light from a laser. The dye converts the laser into heat, which raises the temperature of the liposomal envelope, lyses the liposome, and releases the dye. The ability to control location, timing, and repetition of dye release would allow local flow patterns to be visualized without the background of the underlying choroidal circulation or adjacent vessel networks. The system will make assessment of localized perfusion defects possible. The creation of a better defined wavefront, achieved with the generation of a bolus, opens the way for quantitative measurement of flow. By controlling the time between the release of the dye from the liposomes and the time of recording, we have been able in preliminary studies to measure the velocity of blood in vitro, as well as in the retinal vessels of rabbits and monkeys. Moreover, the possibility of repeating the procedure allows refinement of alignment and focusing of the camera, thereby optimizing the quality of the photographs. Additionally, measurements can be performed before and after induced changes of physiologic conditions (i.e., oxygen or nitrogen breathing, exposure to light or pharmacological agents). The system offers the control of time, location, and repetition of delivery, which potentially will be useful in a number of therapeutic applications as well.