Video game addicts, rejoice: US researchers have found that playing action-packed computer games can be good for your eyes.

A study by scientists at the University of Rochester shows that people who play action video games for a few hours each day over the course of a month can improve their performance in eye examinations by about 20%.

"Action video game play changes the way our brains process visual information," says Daphne Bavelier, professor of brain and cognitive sciences.

"These games push the human visual system to the limits and the brain adapts to it," Bavelier adds. "That learning carries over into other activities and possibly everyday life."

Bavelier and graduate student Shawn Green tested college students who had played very few, if any, video games in the preceding year. "That alone was pretty tough," says Green. "Nearly everybody on a campus plays video games."

Crowded out

Test subjects were given an eye test similar to one used at regular eye clinics. They were asked to identify the position of a "T" within a crowd of other symbols – a so-called "crowding test".

Participants were then divided into two groups. One played the "shoot-em-up" action game Unreal Tournament for an hour a day while the other played the less visually complex computer game Tetris for the same amount of time.

After 30 hours of gaming, both groups had their vision tested again. Those who played Tetris saw no improvement in their test score. However, the group that played Unreal Tournament scored 20% better in the eye test on average.

The researchers believe the spatial resolution of these players' vision had improved as a result of playing the fast and furious computer game. This enabled them to pick out figures on an eye chart more clearly, despite other symbols crowding in.

The researchers say their findings could help patients with certain visual defects such as amblyopia, or "lazy eye". Such people might perhaps benefit from using specially designed training software.

Journal reference: Psychological Science (in press)