Sousa David Cordeiro, Leal Inês, Moreira Susana, do Vale Sónia, Silva-Herdade Ana S, Aguiar Patrício, Dionísio Patrícia, Abegão Pinto Luís, Castanho Miguel A R B, Marques-Neves Carlos
Ophthalmology Department, Hospital de Santa Maria, Centro Hospitalar Universitário Lisboa Norte, Lisbon, Portugal.
Vision Sciences Study Center, CECV, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
Front Neurosci. 2019 Jun 12;13:566. doi: 10.3389/fnins.2019.00566. eCollection 2019.
Optical coherence tomography angiography (OCT-A) is a novel diagnostic tool with increasing applications in ophthalmology clinics that provides non-invasive high-resolution imaging of the retinal microvasculature. Our aim is to report in detail an experimental protocol for analyzing both vasodilatory and vasoconstriction retinal vascular responses with the available OCT-A technology.
A commercial OCT-A device was used (AngioVue, Optovue, CA, United States), and all examinations were performed by an experienced technician using the standard protocol for macular examination. Two standardized tests were applied: (i) the hypoxia challenge test (HCT) and (ii) the handgrip test, in order to induce a vasodilatory and vasoconstriction response, respectively. OCT-A was performed at baseline conditions and during the stress test. Macular parafoveal vessel density of the superficial and deep plexuses was assessed from the angiograms. Statistical analysis was performed using STATA v14.1 and < 0.05 was considered for statistical significance.
Twenty-four eyes of 24 healthy subjects (10 male) were studied. Mean age was 31.8 ± 8.2 years (range, 18-57 years). Mean parafoveal vessel density in the superficial plexus increased from 54.7 ± 2.6 in baseline conditions to 56.0 ± 2.0 in hypoxia ( < 0.01). Mean parafoveal vessel density in the deep plexuses also increased, from 60.4 ± 2.2 at baseline to 61.5 ± 2.1 during hypoxia ( < 0.01). The OCT-A during the handgrip test revealed a decrease in vessel density in both superficial (55.5 ± 2.6 to 53.7 ± 2.9, < 0.001) and deep (60.2 ± 1.8 to 56.7 ± 2.8, < 0.001) parafoveal plexuses.
In this work, we detail a simple, non-invasive, safe, and non-costly protocol to assess a central nervous system vascular response (i.e., the retinal circulation) using OCT-A technology. A vasodilatory response and a vasoconstriction response were observed in two physiologic conditions-mild hypoxia and isometric exercise, respectively. This protocol constitutes a new way of studying retinal vascular changes that may be applied in health and disease of multiple medical fields.
光学相干断层扫描血管造影（OCT-A）是一种新型诊断工具，在眼科诊所的应用日益广泛，可对视网膜微血管系统进行无创高分辨率成像。我们的目的是详细报告一种使用现有OCT-A技术分析视网膜血管舒张和收缩反应的实验方案。
使用一台商用OCT-A设备（美国加利福尼亚州Optovue公司的AngioVue），所有检查均由一名经验丰富的技术人员按照黄斑检查的标准方案进行。应用了两项标准化测试：（i）低氧激发试验（HCT）和（ii）握力试验，以分别诱导血管舒张和收缩反应。在基线条件和应激试验期间进行OCT-A检查。从血管造影图像评估黄斑旁中心凹浅表和深部血管丛的血管密度。使用STATA v14.1进行统计分析，P<0.05被认为具有统计学意义。
对24名健康受试者（10名男性）的24只眼睛进行了研究。平均年龄为31.8±8.2岁（范围18 - 57岁）。浅表血管丛的平均旁中心凹血管密度从基线时的54.7±2.6增加到低氧时的56.0±2.0（P<0.01）。深部血管丛的平均旁中心凹血管密度也增加，从基线时的60.4±2.2增加到低氧时的61.5±2.1（P<0.01）。握力试验期间的OCT-A显示浅表（从55.5±2.6降至53.7±2.9，P<0.001）和深部（从60.2±1.8降至56.7±2.8，P<0.001）旁中心凹血管丛的血管密度均降低。
在这项研究中，我们详细介绍了一种使用OCT-A技术评估中枢神经系统血管反应（即视网膜循环）的简单、无创、安全且成本低廉的方案。在两种生理条件下分别观察到了血管舒张反应和血管收缩反应，即轻度低氧和等长运动。该方案构成了一种研究视网膜血管变化的新方法，可应用于多个医学领域的健康和疾病研究。
