Head-down tilt (HDT) has been widely proposed as a terrestrial analog of microgravity and used also to investigate the occurrence of spaceflight-associated neuro-ocular syndrome (SANS), which is currently considered one of the major health risks for human spaceflight. We propose here an in vivo validated numerical framework to simulate the acute ocular-cerebrovascular response to 6° HDT, to explore the etiology and pathophysiology of SANS. The model links cerebral and ocular posture-induced hemodynamics, simulating the response of the main cerebrovascular mechanisms, as well as the relationship between intracranial and intraocular pressure to HDT. Our results from short-term (10 min) 6° HDT show increased hemodynamic pulsatility in the proximal-to-distal/capillary-venous cerebral direction, a marked decrease (-43%) in ocular translaminar pressure, and an increase (+31%) in ocular perfusion pressure, suggesting a plausible explanation of the underlying mechanisms at the onset of ocular globe deformation and edema formation over longer time scales.

低头倾斜（HDT）已被广泛提出作为微重力的地面模拟，也用于研究航天相关神经眼综合征（SANS）的发生，该综合征目前被认为是人类航天的主要健康风险之一。我们在这里提出了一个体内验证的数值框架来模拟对 6° HDT 的急性眼脑血管反应，以探索 SANS 的病因学和病理生理学。该模型将大脑和眼姿势引起的血流动力学联系起来，模拟主要脑血管机制的反应，以及颅内压和眼内压与 HDT 之间的关系。我们的短期（10 分钟）6° HDT 结果显示，近端到远端/毛细血管静脉大脑方向的血流动力学搏动增加，眼层压显着降低 (-43%)，并且增加 (+31 ％）在眼灌注压中，这对较长时间尺度内眼球变形和水肿形成的潜在机制提出了合理的解释。