At a Glance Astronauts experience cephalad fluid shifts in space, and this can harm ocular health

Many of the issues have been linked to elevations in intracranial pressure – but not all astronauts have this problem

NASA’s ocular health program aims to screen astronauts’ ocular health on the ground and in the ISS to try and understand when and why these changes occur

Successfully understanding the underlying pathologies is key not only to developing prophylactic or treatment strategies – but these findings may also directly impact the future of manned interplanetary space flight

It was an incredible feat of engineering that thrust astronauts into space, and an even greater engineering and political achievement establishing the International Space Station (ISS). But why stop there? NASA intends to send a manned mission to Mars, which will hopefully represent humankind’s greatest space exploration achievement. However, having never evolved in microgravity, humans aren’t built for space travel. Indeed, the medical implications of being in space aren’t trivial (see Table 1 below), and these need to be better understood before humankind can boldly go anywhere in the cosmos for any length of time. Unfortunately, ocular health is something that the microgravity environment in space has the potential to seriously and permanently harm (see Table 2 below).