颈动脉内膜中层厚度对2型糖尿病患者黄斑区视网膜微循环的影响:基于OCTA观察

目的　应用光学相干断层扫描血管成像（OCTA）技术定量分析颈动脉内膜中层厚度（IMT）对2型糖尿病无糖尿病视网膜病变（NDR）患者黄斑中心凹无血管区(FAZ) 面积、周长、形态指数和黄斑区血流密度(VD) 的影响及其临床意义。方法　横断面研究。本研究收集2020年9月至2021年5月于本院内分泌科确诊为2型糖尿病，且经颈动脉彩色超声检查显示仅一侧颈动脉IMT增厚且无DR的患者30例（60眼），双眼及双侧颈动脉均入组，并根据测得的颈动脉IMT厚度分为IMT增厚组30眼和IMT正常组30眼。应用OCTA对受试眼黄斑区视网膜3 mm×3 mm区域进行扫描，获得视网膜浅层毛细血管图像，将所得图像划分为以黄斑中心凹为中心直径1 mm和3 mm的内外2个同心圆，软件自动测得黄斑中心凹（1 mm×1 mm）、旁中心凹（1～3 mm）4个方位（鼻侧、颞侧、上方、下方）血流密度(VD)及FAZ面积、周长和形态指数,对所有受试者行双侧颈动脉彩色超声检查，计算平均颈动脉IMT，并比较两组患者各指标间的差异。结果　IMT增厚组和IMT正常组患者FAZ周长、面积、形态指数、黄斑中心凹VD分别为(2.74±0.40) mm和(2.50±0.30) mm、（0.37±0.14）mm²和（0.32±0.09）mm² 、0.60±0.11和0.66±0.53、（14.98±4.56）%和（18.02±2.70）%，两组间比较差异均有统计学意义（均为P<0.05）。IMT增厚组患者黄斑旁中心凹4个方位（颞侧、鼻侧、上方、下方）VD分别为（47.16±3.58）%、（46.33±3.59）%、（45.76±3.28）%、（49.39±2.94）%，IMT正常组患者黄斑旁中心凹4个方位（颞侧、鼻侧、上方、下方）VD分别为（47.65±3.26）%、（46.39±3.32）%、（47.18±4.18）%、（48.77±3.70）%，两组间比较差异均无统计学意义（均为P>0.05）。相关性分析显示，颈动脉IMT与FAZ周长呈正相关（r=0.329，P=0.01），与FAZ形态指数、黄斑中心凹VD均呈负相关（r=-0.342、-0.312，均为P＜0.05）。结论　伴NDR的2型糖尿病患者可表现为视网膜微循环障碍。在糖尿病早期，颈动脉IMT与视网膜微循环相关指标的改变有关。颈动脉IMT可作为评估 2 型糖尿病患者早期微血管病变的一种筛查手段。

Effect of carotid intima-media thickness on the retinal microcirculation in the macular area of type 2 diabetic patients based on optical coherence tomography angiography

Objective　To quantitatively analyze the effect of carotid intima-media thickness (IMT) on the area, circumference and morphology of the foveal avascular zone (FAZ), as well as the macular vascular density (MVD) in type 2 diabetic patients with non-diabetic retinopathy (NDR) and its clinical significance using the optical coherence tomography angiography (OCTA).Methods　This study was a cross-sectional study. Thirty patients (60 eyes) who were clinically diagnosed with type 2 diabetes in the Department of Endocrinology of Wuhan Hospital of Integrated Traditional Chinese and Western Medicine from September 2020 to May 2021 were selected. The initial carotid artery color Doppler ultrasound screening showed that all these patients had unilateral IMT thickened and no retinopathy. In this study, both eyes and bilateral carotid arteries were included in the groups. According to the measured carotid IMT thickness, patients were equally divided into the thickened IMT group (30 eyes) and normal IMT group (30 eyes). OCTA was used to scan the 3 mm×3 mm area in the macular retina of all test eyes to obtain the superficial retinal capillary layer image. The obtained image was divided into two concentric circles with a diameter of 1 mm and 3 mm centered on the macular fovea. The software automatically measured the vascular density (VD) in the central fovea (1 mm×1 mm) and four sites (nasal, temporal, superior, and inferior) of the parafovea (1-3 mm), as well as the area, circumference and morphology of FAZ. All patients received the bilateral carotid artery color doppler ultrasound examination. The average carotid IMT was calculated, and differences in each index between the two groups were compared. Results　The FAZ circumferences of the thickened IMT group and the normal IMT group were (2.74±0.40) mm and (2.50±0.30) mm, respectively; the FAZ areas were (0.37±0.14) mm² and (0.32±0.09) mm², respectively; the FAZ morphological index were 0.60±0.11 and 0.66±0.53, respectively; and the foveal VDs were (14.98±4.56)% and (18.02±2.70)%, respectively. The differences between the two groups were statistically different (all P<0.05). In the thickened IMT group, the VDs in the four sites (temporal, nasal, superior, and inferior) of the parafovea were (47.16±3.58) %, (46.33±3.59) %, (45.76±3.28) %, and (49.39±2.94) %, respectively, while in the normal IMT group, the VDs in the four sites (temporal, nasal, superior, and inferior) of the parafovea were (47.65±3.26) %, (46.39±3.32) %, (47.18±4.18) %, and (48.77±3.70) %, respectively. There were no statistically significant differences between the two groups (all P>0.05). Correlation analysis showed that the carotid IMT is positively correlated with FAZ circumference (r=0.329, P=0.01), and negatively correlated with FAZ morphological index, macular foveal VD (r=-0.342 and -0.312, both P<0.05). Conclusion　Diabetic patients without diabetic retinopathy may have retinal microcirculation disorders. In the early stage of diabetes, carotid IMT is associated with changes in retinal microcirculation related indicators. Carotid IMT can be used as a screening method to assess the occurrence of early microvascular complications in patients with type 2 diabetes.