宇航员马克·凡德·黑在空间站接受眼睛检查
NASA astronaut Mark Vande Hei peers into near-infrared medical-imaging gear, or optical coherence tomography, for detailed views of his retina as part of regularly scheduled eye checks aboard the International Space Station. Astronauts periodically check their eyes because of a phenomenon known as Space-Associated Neuro-Ocular Syndrome (SANS). Symptoms inclu...