It's not really why he signed up to be an astronaut, but like it or not, Mike Barratt and his eyes have become a science project.
The eye charts he reads, the red drops that turn his eyes yellow and the ultrasounds being performed on him could determine whether he or any other astronaut ever journeys into deep space or sets foot on other worlds.
NASA's new priority is how to protect astronauts from going blind on the years-long trip to get wherever they are going.
"I absolutely agree that this is our number one priority," Barratt said
In the past few years, about half of the astronauts aboard the international space station have developed an increasing pressure inside their heads, an intracranial pressure that reshapes their optic nerve, causing a significant shift in the eyesight of male astronauts. Doctors call it papilledema.
Female space travelers have not been affected.
Some of the astronauts slowly recover. Others have not.