There are many risks involved in spaceflight. Eye damage is one of stealthiest. NASA has documented at least seven cases where astronauts with healthy eyes returned to Earth with altered vision. For some, vision loss lasts only a few weeks. Others must live with the condition for much longer and in some cases it may not resolve. The cause remains unknown, but one possible culprit is elevated intracranial pressure caused by an extended stay in microgravity.
Space Oddity: NASA documented at least seven cases where astronauts with healthy eyes returned to Earth with altered vision.
A prototype of a space ultrasound probe.
Scientists from GE Global Research are helping NASA find the cause. They are building a new ultrasound probe and measurement techniques for tracking changes in astronaut vision. The aim of this probe is to deliver real-time, three dimensional pictures showing the entire globe of the eye and potential changes in its structure and functionality. “Spaceflight causes fluid to pool in the upper body and head, resulting in increased pressure in the head and the optic nerve,” says Aaron Dentinger, an electrical engineer in the Ultrasound Systems Lab at GE Global Research. “That could trigger a change in the shape of the eye leading to vision problems. So far, mild vision changes have been observed, but the potential for permanent damage is a major concern on longer term missions, making real-time monitoring in space crucial so that NASA can evaluate treatments.”
The scientists hope that the research could also advance the understanding of the underlying causes of traumatic brain injuries and lead to better monitoring of changes in brain pressure in people who sustain violent blows to the head.
A commercially available GE ultrasound machine already operates on the International Space Station. GE’s Vivid q cardiovascular ultrasound system was delivered during the space shuttle’s final flight a year ago. The new research, which will last for three years, could add new insight to the use of the instrument to image blood vessels around the eye.