Doheny Eye Institute, Los Angeles, California, United States.
Department of Ophthalmology, Shinshu University School of Medicine, Nagano, Japan.
Sci Rep. 2018 Jun 20;8(1):9380. doi: 10.1038/s41598-018-27536-5.
Optical coherence tomography angiography (OCTA) allows the retinal microvasculature to be visualized at various retinal depths. Previous studies introduced OCTA axial profile analysis and showed regional variations in the number and location of axially distinct vascular retinal plexuses. OCTA acquisition and processing approaches, however, vary in terms of their resulting transverse and axial resolutions, and especially the latter could potentially influence the profile analysis results. Our study imaged normal eyes using the Spectralis OCT2 with a full-spectrum, probabilistic OCTA algorithm, that, in marked contrast to split-spectrum approaches, preserves the original high OCT axial resolution also within the resulting OCTA signal. En face OCTA images are generally created by averaging flow signals over a finite axial depth window. However, we assessed regional OCTA signal profiles at each depth position at full axial resolution. All regions had two sharp vessel density peaks near the inner and outer boundaries of the inner nuclear layer, indicating separate intermediate and deep capillary plexuses. The superficial vascular plexus (SVP) separated into two distinct peaks within the ganglion cell layer in the parafoveal zone. The nasal, superior, and inferior perifovea had a deeper SVP peak that was shifted anteriorly compared to the parafoveal zone. Axial vascular density analysis with high-resolution, full spectrum OCTA thus allows healthy retinal vasculature to be precisely reconstructed and may be useful for clinically assessing retinal pathology.
光学相干断层扫描血管造影术（OCTA）可以在不同的视网膜深度可视化视网膜微血管。先前的研究介绍了 OCTA 轴向剖面分析，并显示了轴向不同血管视网膜丛的数量和位置的区域变化。然而，OCTA 的采集和处理方法在其横向和轴向分辨率方面有所不同，特别是后者可能会影响剖面分析结果。我们使用 Spectralis OCT2 对正常眼睛进行成像，该仪器采用全谱、概率 OCTA 算法，与分谱方法形成鲜明对比的是，该算法在产生的 OCTA 信号中也保留了原始的高 OCT 轴向分辨率。En face OCTA 图像通常是通过在有限的轴向深度窗口上对血流信号进行平均来创建的。然而，我们在全轴向分辨率下评估了每个深度位置的局部 OCTA 信号曲线。所有区域在内核层的内界和外界附近都有两个尖锐的血管密度峰值，表明存在单独的中间和深层毛细血管丛。浅层血管丛（SVP）在旁中心凹区域的神经节细胞层中分为两个明显的峰值。鼻侧、上侧和下侧旁中心凹的浅层血管丛峰值较深，且向前移位。高分辨率、全谱 OCTA 的轴向血管密度分析可以精确重建健康的视网膜血管，可能有助于临床评估视网膜病变。
