Playing video games is good for you - or so say researchers at the US University of Rochester who found that gaming actually improves your eyesight.

Daphne Bavelier, professor of brain and cognitive sciences, put a group of students in front of first person shooter Unreal Tournament for an hour a day for 30 days.

Professor Bavelier tested the students before and after the game, measuring how fast they could recognise a specific figure in a busy image. The result was a shock 20% improvement in their eyesight.

"Players showed a substantial increase in the spatial resolution of their vision," said Professor Bavelier.

"They could see figures like those on an eye chart more clearly, even when other symbols crowded in."

In comparison, a second group were tasked with playing Tetris under similar conditions. While demanding, Tetris doesn't require the player to spot different objects as quickly.

"When people play action games, they're changing the brain's pathway responsible for visual processing," says Bavelier.

Games like Unreal Tournament often push the human visual system "to the limit" and the brain adapts, ultimately using these new skills in every day life.

Researchers say their findings could eventually help people with visual defects - like amblyopia (aka lazy eye) - with the development of rehabilitation software.