ELK CITY, Oklahoma - A software program created by two doctors in Oklahoma is on its way right now to the International Space Station.

NASA is calling on two of Oklahoma's own for a new research study. For years, NASA has been saying its astronauts are coming back with vision issues after long-term stays on the station. That's why it's investigating effects of microgravity on astronauts' vision, hoping to get some answers with the help of two Oklahoma doctors.

From his office in Elk City, Dr. Daniel Bintz uses a digital eye chart that he and Dr. Jerry Carter of Bartlesville, created more than a dozen years ago. Since then, they've sold licenses for Acuity Pro around the world, but at a recent conference they got a buyer they never expected: NASA.

"When they came back to us a couple months later and said they wanted a demo and wanted to know more about the program, we were pretty excited about it," Bintz said, "I've been a space nut since I grew up."

Around 4 p.m. Thursday, a spacecraft launched from Russia carrying Bintz's software on about 20 laptop computers. It's being used to check how quickly astronauts' vision is changing.

"We were kind of built for gravity," Bintz said. "So when you're in space and there's no gravity, your body doesn't react the same way. And one of the problems they're having is with cerebral spinal fluid not flowing the right way."

That causes swelling in the brain and the optic nerve, most of the time, causing astronauts to become far-sighted.

"The optic nerve is basically your ‘TV cable' that takes everything back to the brain. And if it's swollen, you may get blind spots or grayed out areas," Bintz said.

Bintz says it's rewarding to think his idea could bring answers to a problem that so far, has gone unsolved.

"It's kind of neat that we had something here that they actually wanted," Bintz said.

NASA says two out of every 10 astronauts return with eye problems, some permanent. The study starts April 1 and will last about two years