Age-related macular degeneration (AMD) is a vision-threatening disease that affects the outer retina and choroid of elderly adults. Because photoreceptors are found in the outer retina and rely primarily on the trophic support of the underlying choriocapillaris, imaging of flow or lack thereof in choriocapillaris by optical coherence tomography angiography (OCTA) has great clinical potential in AMD assessment. We introduce a metric using OCTA, named "focal perfusion loss" (FPL) to describe the effects of age and non-neovascular AMD on choriocapillaris flow. Because OCTA imaging of choriocapillaris is vulnerable to artifacts-namely motion, projections, segmentation errors, and shadows-they are removed by postprocessing software. The shadow detection software is a machine learning algorithm recently developed for the evaluation of the retinal circulation and here adapted for choriocapillaris analysis. It aims to exclude areas with unreliable flow signal due to blocking of the OCT beam by objects anterior to the choriocapillaris (e.g., drusen, retinal vessels, vitreous floaters, and iris). We found that both the FPL and the capillary density were able to detect changes in the choriocapillaris of AMD and healthy age-matched subjects with respect to young controls. The dominant cause of shadowing in AMD is drusen, and the shadow exclusion algorithm helps determine which areas under drusen retain sufficient signal for perfusion evaluation and which areas must be excluded. Such analysis allowed us to determine unambiguously that choriocapillaris density under drusen is indeed reduced.

中文翻译：

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在中度，非血管性年龄相关性黄斑变性中检测和测量脉络膜毛细血管低灌注区域。

年龄相关性黄斑变性（AMD）是一种威胁视力的疾病，会影响老年人的外视网膜和脉络膜。因为感光细胞存在于视网膜的外部，并且主要依赖于潜在脉络膜毛细血管的营养支持，所以通过光学相干断层扫描血管造影术（OCTA）对脉络膜毛细血管中血流的缺乏或缺乏进行成像，在AMD评估中具有巨大的临床潜力。我们引入了一种使用OCTA的度量，称为“局部灌注损失”（FPL），以描述年龄和非血管性AMD对脉络膜毛细血管流量的影响。由于脉络膜毛细血管的OCTA成像易受伪影（即运动，投影，分割错误和阴影）的影响，因此可以通过后处理软件将其删除。阴影检测软件是最近开发的一种用于评估视网膜循环的机器学习算法，适用于脉络膜毛细血管分析。它的目的是排除脉络膜毛细血管之前的物体（如玻璃疣，视网膜血管，玻璃体漂浮物和虹膜）阻塞OCT束而导致流量信号不可靠的区域。我们发现FPL和毛细血管密度均能够检测AMD和健康的年龄匹配受试者相对于年轻对照的脉络膜毛细血管的变化。AMD中阴影形成的主要原因是玻璃疣，阴影排除算法有助于确定玻璃疣下哪些区域保留了足够的信号以进行灌注评估，哪些区域必须排除。