San Francisco  A new study has found that action video games can improve players' eyesight, researchers said Monday.  The study, which was published in the journal Nature Neuroscience, found that the visual processes needed to play games like Call of Duty 2 improved players' contrast sensitivity. Contrast sensitivity allows people to notice different shades and is particularly important for such tasks as driving at night and discerning patterns and facial expressions.

"Normally, improving contrast sensitivity means getting glasses or eye surgery - somehow changing the optics of the eye," Daphne Bavelier, professor of brain and cognitive sciences at the University of Rochester, said in a statement. "But we've found that action video games train the brain to process the existing visual information more efficiently, and the improvements last for months after game play stopped."

Bavelier and other researchers studied two groups that played video games for 50 hours during over a nine-week period. The group that played shooting action games like Call of Duty 2 and Unreal Tournament registered enhanced contrast sensitivity compared to those in the group that played non-action games such as Sims 2, which doesn't require precise visually guided aiming actions in high stress situations.

"When people play action games, they're changing the brain's pathway responsible for visual processing," Bavelier said. "These games push the human visual system to the limits and the brain adapts to it, and we've seen the positive effect remains even two years after the training was over."

This suggests that the effect of the video game training could provide an alternative to eyeglasses or surgery for those with diminished contrast sensitivity.