Objective: To quantify optical coherence tomographic angiography (OCTA) images and to explore potential clinical values of each parameter in diabetic patients. Methods: A case-control and cross-sectional study of diabetic (129 eyes) and healthy (32 eyes) subjects was conducted. 3-mm OCTA scan, fundus photography and best corrected visual acuity measurement were performed. Image-pro plus was used to calculate microvascular and foveal avascular indices in nonsegmented and segmented OCTA images. Intraclass correlation coefficient and relative standard deviation were used to examine the reliability, reproducibility and accuracy. Correlation of each parameter was calculated, and so was the area under the receiver operating characteristic curve. Results: Vessel density (VD) of diabetic patients measured in the nonsegmented retinal layer (RL) and superficial retinal layer (SRL) was 49.146%±6.097%, 44.038%±5.641%, respectively, significantly lower than healthy subjects 52.212%±6.250%, 46.698%±5.417% (t=2.534, 2.405; P=0.012, 0.017), and vessel length (VL) was (19.905±2.285)mm, (17.596±2.149)mm, (14.479±2.091)mm in the three layers, which was significantly shorter than that in the healthy control group (21.037±2.185)mm, (18.739±1.994)mm, (15.343±2.266)mm (t=2.529, 2.731, 2.059; P=0.012, 0.007, 0.041). Compared with non-diabetes, foveal avascular zone (FAZ) in diabetes was (0.441±0.167)mm(2), larger compared to health eyes 0.352±0.109mm(2) (t=-2.831, P=0.005). FAZ demonstrated a negative correlation with VD and VL in RL or SRL(r=-0.227, -0.338; P<0.05) (r=-0.241, -0.332; P<0.05), while best corrected visual acuity showed a negative correlation with VL in each layer (r=-0.225, -0.201, -0.250; P=0.01, 0.022, 0.004), and VD in DRL (r=-0.197, P=0.026). All parameters showed high reproducibility between graders(intraclass correlation coefficient>0.965), while relative standard deviation was greater than 3.049%. AR had the highest area under the receiver operating characteristic curve (0.737), compared with AI (0.724). Conclusions: Our study demonstrates good reliability, reproducibility and accuracy of quantification of OCTA images and reveals changes of VD, VL and FAZ in diabetes, which may occur earlier than vision impairment. AR and AL may have great values in prompting early diabetic retinopathy in diabetic patients. (Chin J Ophthalmol, 2019, 55:273-279).
目的： 探讨2型糖尿病患者相干光层析血管成像术（OCTA）图像量化效果，以及量化后各参数的变化及临床意义。 方法： 横断面研究。糖尿病组受试者纳入苏州大学附属理想眼科医院糖尿病视网膜病变防治小组于2017年9至12月招募的2型糖尿病视网膜病变患者105人（129只眼），其中男性47例，女性58例，年龄（61.41±8.44）岁；健康对照组为非糖尿病志愿者27名（32只眼），其中男性14名，女性13名，年龄（64.13±8.10）岁。对两组进行OCTA、眼底照相及最佳矫正视力（BCVA）检查。采用Image-pro plus对所有OCTA图像进行量化分析，组间各参数比较采用两独立样本t检验，各参数与BCVA的相关性采用Spearman检验，并进行方法的可靠性可重复性（ICC）和精确性（RSD）检验，通过受试者工作特征（ROC）曲线验证各参数对于糖尿病视网膜病变的诊断效率。 结果： 糖尿病组的血管密度在未分层视网膜及浅层视网膜上分别为49.146%±6.097%，44.038%±5.641%，显著低于健康对照组52.212%±6.250%，46.698%±5.417%（t=2.534，2.405；P<0.05）。糖尿病组的血管总长度在3层血管图中分别为（19.905±2.285）、（17.596±2.149）、（14.479±2.091）mm，均显著低于健康对照组的（21.037±2.185）、（18.739±1.994）、（15.343±2.266）mm（t=2.529，2.731，2.059；P<0.05）。糖尿病组的黄斑无血管区面积为（0.441±0.167）mm(2)，显著大于健康对照组（0.352±0.109）mm(2)（t=-2.831；P=0.005）。其他的参数两组间差异均无统计学意义（P>0.05）。糖尿病组BCVA与深层视网膜的血管密度（r=-0.197，P=0.026）及3层血管图的血管总长度均呈负相关（r=-0.225，-0.201，-0.250；P<0.05）。与其余的参数均无明显相关（P>0.05）。各个参数的ICC值均>0.965，而RSD均<3.049%。轴率的ROC曲线下面积（AUC）为0.737，非圆系数的AUC为0.724。 结论： 该OCTA检查结果图像量化方法的可靠性、可重复性及精确性较好。糖尿病患者血管密度、血管长度及无血管区的改变可出现在视力受损之前，而无血管区形态改变对于糖尿病视网膜病变的早期诊断具有指导意义。（中华眼科杂志，2019，55：273-279）.
Keywords: Angiography; Diabetes mellitus, type 2; Retinal vessels; Tomography, optical coherence.