Your mom was wrong — not all video games are bad for you.

A study conducted by researchers at McMaster University indicates that playing first person shooter games can help improve the eyesight of people with conditions like amblyopia or cataracts.

"Parents are always concerned their kids are playing too many video games," said Terri Lewis, a vision scientist who was part of the team that conducted the study.

"Now, many people are saying 'Well, I'm not going to nag my kids anymore.'"

A paper by Simon Jeon that outlines the results of the study was published in the journal Seeing and Perceiving in August.

Researchers at McMaster had seven people with pre-existing eye conditions play Medal of Honor, which was released on the Xbox 360 in 2010.

Participants were all born with cataracts that were removed — but because of their condition, their vision never developed to 20/20. Six of the seven were not gamers.

They played the game for 10 hours straight in a controlled environment, and then two hours a day only until they reached 40 hours of play.

"We brought them back four weeks later and they all had improved vision," Lewis said.

The participants found improvements in detail, perception of motion and in low contrast settings.

In essence, players could now read about one to one-and-a-half more lines on an optometrist's eye chart.

"We were thrilled," Lewis said. "It's very exciting to open up a new world of hope for these people."

Researchers don't know exactly how playing the game was able to help restore some vision for the patients.

They hypothesize the adrenaline created playing the came creates dopamine — which when combined with the level of attention to detail players need in a Medal of Honor match — can actually rewire visual connections in the brain.

"You're required to be extremely alert when playing," Lewis said. "You have to be ready to shoot to kill at all times."

Interestingly, the team didn't get the same result from other, less intense games like Tetris or The Sims.

Lewis says that without the urgent adrenaline rush that comes from playing a first person shooter, the results just don't happen.

She said her colleagues are now trying to develop something less aggressive that has the same sort of characteristics so the treatment can be used on children, too.

"We don't feel comfortable administering these games to children," she said.

Lewis says the treatment wouldn't work on individuals who have physical eye problems, like a detached retina.

Armed with these results, the McMaster team is trying to challenge the belief that a person's vision won't improve past childhood.

"Now, maybe even as an adult, you can do things to improve your vision," she said.

For more on the Visual Development Lab and their work, click here.