不同分层、不同区域增生型糖尿病视网膜病变患眼视网膜毛细血管无灌注区的分布特征:基于全域SS-OCTA的研究

目的　采用全域扫频源光相干断层扫描血管成像（SS-OCTA）探讨不同分层、不同区域增生型糖尿病视网膜病变（PDR）患眼视网膜毛细血管无灌注区（NPA）的分布特征。方法　将2021年12月至2022年1月在潍坊医学院附属医院眼科确诊的PDR患者21例（26眼）纳入本研究。采用图湃（北京）医疗科技有限公司生产的BM-400K行全域SS-OCTA检查，采集患者视网膜浅层毛细血管层（SCP）和深层毛细血管层（DCP）图像。每层均按照两种方法分区:（1）以黄斑中心凹中点为圆心分为不同的圆环区域，以中央直径1 mm的圆为黄斑中心凹无血管区，直径1~<3 mm为最内环，3~<6 mm为内环，6~<10 mm为中环，≥10 mm至视网膜边界为外环（由于最内环毛细血管是相连的无缝网络且被重叠灌注，不易形成NPA，因此本次主要检测和比较内环、中环和外环的NPA）；（2）以黄斑中心凹中点作水平线和垂直线，将视网膜分为颞上、颞下、鼻上、鼻下四个象限。分别测量内环、中环、外环及四个象限的NPA面积并计算缺血指数（ISI），比较PDR患眼SCP、DCP不同圆环区域和不同象限的NPA面积和ISI，分析NPA分布特征。结果　PDR患眼DCP NPA总面积［（124.340±54.971）mm²］大于SCP［（119.119±55.279）mm²］，DCP 总ISI（0.423 0±0.187 0）大于SCP总ISI（0.405 0±0.188 0），差异均有统计学意义（均为P<0.001）。SCP、DCP外环NPA面积大于中环，中环大于内环，差异均有统计学意义（均为P<0.05）；SCP、DCP外环ISI大于中环，中环大于内环，差异均有统计学意义（均为P<0.05）。SCP、DCP颞下象限NPA面积大于鼻上象限，差异均有统计学意义（均为P<0.05），其余象限比较，差异均无统计学意义（均为P>0.05）；SCP、DCP颞下象限ISI大于鼻上象限，差异均有统计学意义（均为P<0.05），其余象限比较，差异均无统计学意义（均为P>0.05）。结论　PDR患眼视网膜NPA分布不均衡，在DCP、外环和颞下象限具有更多的NPA。

Distribution characteristics of the retinal capillary non-perfusion area at different layers and zones in patients with proliferative diabetic retinopathy based on full-range swept-source optical coherence tomography angiography

Objective　To explore the distribution characteristics of the retinal capillary non-perfusion area (NPA) at different layers and zones in patients with proliferative diabetic retinopathy (PDR) using the full-range swept-source optical coherence tomography angiography (SS-OCTA).
Methods　Twenty-one PDR patients (26 eyes) diagnosed in the Ophthalmology Department of Affiliated Hospital of Weifang Medical University from December 2021 to January 2022 were included in this study. Full-range SS-OCTA was performed using BM-400K of TowardPi (Beijing) Medical Technology Ltd. to collect images of superficial capillary plexus (SCP) and deep capillary plexus (DCP). Each layer was zoned via two approaches: (1) The retina was divided into different circles centered on the midpoint of the fovea. A circle with a diameter of 1 mm was defined as the foveal avascular zone (FAZ). Circles with a diameter of 1-3 (exclusive) mm, 3-6 (exclusive) mm, 6-10 (exclusive) mm, and 10 mm or above were defined as the innermost, inner, intermediate, and outer rings, respectively. Capillaries in the innermost ring were connected closely and often overlapped, which hardly formed NPA; therefore, NPAs at the inner, intermediate and outer rings were mainly measured and compared in this study; (2) The retina was divided into the superotemporal, inferotemporal, superonasal, and inferonasal quadrants by a horizontal and a vertical line through the midpoint of the fovea. NPAs at the inner, intermediate, and outer rings, as well as at the four quadrants were measured, and the ischemic index (ISI) was calculated. The NPA and ISI at the different concentric circles and quadrants of SCP and DCP in all the PDR patients were compared, and then the distribution characteristics of NPA were analyzed.
Results　The NPA of DCP ［(124.340±54.971) mm²］ was larger than that of SCP ［(119.119±55.279) mm²］, the ISI of DCP (0.423 0±0.187 0) was greater than that of SCP (0.405 0±0.188 0), and the differences were statistically significant (both P<0.001). The NPA and ISI at the outer ring were more than those at the intermediate ring, and the NPA and ISI at the intermediate ring were more than those at the inner ring in both SCP and DCP (all P<0.05). The NPA and ISI at the inferotemporal quadrant were greater than those at the superonasal quadrant in both SCP and DC (all P<0.05), but no statistically significant differences were found in the other quadrants (all P>0.05).
Conclusion　The distribution of retinal NPA in PDR patients is uneven. There are more NPAs in DCP, outer ring, and inferotemporal quadrant.