Department of Ophthalmology, Tokyo Women's Medical University School of Medicine, 8-1 Kawada-cho, Shinjuku, Tokyo, Japan.
Sci Rep. 2018 Oct 24;8(1):15694. doi: 10.1038/s41598-018-34102-6.
Optical coherence tomography angiography (OCTA) seems not to image the choroidal blood flow pattern in the normal individual because of the OCT light attenuation. Our purpose in the current study was to visualize the large choroidal blood flow pattern after subtraction of the choriocapillaris projection artifact in normal eyes non-invasively by swept source (SS) OCTA. Sixty-one eyes of 45 individuals (19 men, 26 women) without ocular disease were examined by SS-OCTA (AngioPlex Elite 9000, Zeiss, Germany). A 12 × 12 mm macular area was scanned. Subfoveal choroidal thickness (SCT) was measured, and the choroidal blood flow pattern in a slab of 30 µm width at one-half of SCT was analyzed. In examining the choroidal blood flow pattern, a slab that was between 30 to 60 µm posterior to the retinal pigment epithelium, in which the choriocapillaris blood flow was most clearly imaged, was used for the subtraction of the projection artifacts from the choriocapillaris on the stromal area of choroid. The ratio (%) of the choroidal blood flow area in the whole choroidal region was calculated after binarization. Thirty-four eyes of 27 individuals (12 men, 15 women) were also examined by spectral domain OCTA (SD-OCTA). After the subtraction, the middle and large choroidal blood flow were clearly visible in SS-OCTA in all eyes. The mean SCT was 297 ± 61 µm, and the mean ratio of the choroidal blood flow area was 27.3 ± 8.2%, which was significantly correlated with SCT (R = 0.738, P < 0.01). SD-OCTA did not show the choroidal blood flow pattern. In conclusion, removal of the projection artifacts of choriocapillaris can make the choroidal blood flow visible in SS-OCTA of normal eyes. Because the ratio of choroidal blood flow area was correlated with SCT, the choroidal blood flow might be an important factor related to the choroidal thickness.
光学相干断层扫描血管造影（OCTA）似乎无法成像正常个体的脉络膜血流模式，因为 OCT 光衰减。我们目前的研究目的是通过扫频源（SS）OCTA 非侵入性地减去脉络膜毛细血管投影伪影，可视化正常眼中的大脉络膜血流模式。对 45 名个体（19 名男性，26 名女性）的 61 只眼进行 SS-OCTA（AngioPlex Elite 9000，蔡司，德国）检查。扫描 12×12mm 黄斑区。测量中心凹下脉络膜厚度（SCT），并分析 SCT 厚度的一半处 30µm 宽的脉络膜血流模式。在检查脉络膜血流模式时，使用视网膜色素上皮后 30 到 60µm 之间的一块板，在该板中脉络膜毛细血管血流成像最清晰，用于从脉络膜基质区减去脉络膜毛细血管的投影伪影。在二值化后计算整个脉络膜区域的脉络膜血流面积的百分比（%）。还对 27 名个体（12 名男性，15 名女性）的 34 只眼进行了光谱域 OCTA（SD-OCTA）检查。减去后，所有眼睛的 SS-OCTA 中均清晰可见中大和大脉络膜血流。平均 SCT 为 297±61µm，脉络膜血流面积比为 27.3±8.2%，与 SCT 显著相关（R=0.738，P<0.01）。SD-OCTA 未显示脉络膜血流模式。总之，去除脉络膜毛细血管的投影伪影可以使 SS-OCTA 中的正常眼脉络膜血流可见。由于脉络膜血流面积比与 SCT 相关，因此脉络膜血流可能是与脉络膜厚度相关的重要因素。
