ISS experiment: Why does space change vision?

NASA astronaut Michael Hopkins, Expedition 37 flight engineer, performs ultrasound eye imaging in the Columbus laboratory of the International Space Station. European Space Agency astronaut Luca Parmitano, flight engineer, assists Hopkins. (Credit: NASA)

Chuck Bednar for redOrbit.com @BednarChuck

A new experiment, scheduled to launch to the International Space Station in the spring, plans to take a long look at vision changes often experienced by astronauts during extended spaceflights, NASA officials announced on Tuesday.

The cause of these vision issues is called visual impairment and intracranial pressure syndrome (VIIP), and according to the US space agency, it involves changes not only in the sense of sight but the structure of the eyes and indirect signs of increases pressure on the brain.

A shift in fluids

The human body is roughly 60 percent fluids, and in space, these fluids shift to the upper part of the body, moving across blood vessels and cell membranes in a different way than they do on Earth. The upcoming Fluid Shifts study will test the relationship between this phenomenon and VIIP, which reportedly affects over half of all US astronauts during extended spaceflights.

Learning more about how blood pressure in the brain affects vision and eye shape could also help those on Earth dealing with conditions that increase swelling and pressure in the eye, as well as though who have been placed on extended periods of bed rest.

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Our first aim is to assess the shift in fluids, to see where fluids go and how the shift varies in different individuals, explained Dr. Michael B. Stenger of the Wyle Science Technology and Engineering Group, one of the principal investigators of the Fluid Shifts project.

The second goal, Stenger added, is to correlate fluid movement with changes in vision, the structure of the eye, and other elements of VIIP syndrome. A third objective is to evaluate the application of negative pressure to the lower body, with the intention of preventing or reversing fluid shifts and determining if this can prevent vision changes from occurring.

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ISS experiment: Why does space change vision?