Fluid distribution in space flight and impact on brain and vision health is an emerging field of high-priority research in the NASA human space program. American astronauts have developed ocular refraction change after space flight on the International Space Station (ISS), in addition to other physiological and anatomical changes in the eye, optic nerve, and brain. Within this book, experts review current data related to fluid shifts during microgravity exposure and the impact of fluid shifts on astronaut health.This work also compares current astronaut health problems with Earth-based health conditions such as elevated ICP and glaucoma. Chapters include alterations in fluid distribution, including intra/extracellular and intra/extravascular fluid shifts, eye morphology and vision disturbances, and intraocular pressure as well as a discussion of modern advanced non-invasive assessment technologies to investigate the abovementioned fluid alterations.As such, the book aims to bridge clinicians, eye researchers, and science professionals with present human space program research, thus providing new perspectives to solve emerging brain and eye disease on Earth and in Space.