Outer space can be hard on the eyes.

Exposure to radiation, intense and ultraviolet light, and low gravity cause blood to rise into the head. Because of this, 34 percent of astronauts experience some kind of vision change while in space.

Testing vision while in flight, however, can be a challenge. Systems that test sight, to include peripheral vision, are bulky, making them impractical for space travel.

"Most of these devices are actually at an ophthalmologist's office," said Wolfgang Fink, Ph.D., founder of the University of Arizona Visual and Autonomous Exploration Systems Research Laboratory. "So, in other words, they are not portable. One cannot self administer them."

Fink, who has degrees in theoretical physics, physics and physical chemistry, is one of several researchers from around the country who have developed a vision-testing system that is the size of an iPad, and which astronauts can use at their leisure. The process takes a few minutes and results are returned right away.