Playing violent, intense-action video games may enhance teenagers eyesight, according to a study in the May issue of Nature Neuroscience. In contrast, the authors found no visual improvement in teenagers who played a slower, non-violent game.

The study authors recruited 22 game-playing teenagers and assessed their contrast sensitivity function (CSF). Then, the subjects were randomized into either the violent video game group (playing Unreal Tournament 2004 or Call of Duty 2) or the slower, non-violent game group (The Sims 2). After the participants logged 50 hours of gaming over a nine-week period, the authors reevaluated the teens CSF.

On average, subjects in the violent video game group demonstrated a 43% improvement in CSF, while subjects in the other group showed no improvement.

The authors concluded that playing violent video games, especially first-person shooter games, enhances gamers ability to discriminate between subtle contrasts in color or shades of gray. Also, the authors believe that action-oriented video games can improve how young gamers brains process visual information. Above all, these enhanced effects appear to last for months after frequent play stops.

I can see how playing intense action video games will enhance visual attention and function much like some optometric vision therapy, says Yin Tea, O.D., associate professor of optometry and chief of pediatrics and binocular vision at Nova Southeastern University College of Optometry.

Many action video games require children to process and respond to visual information quickly and accurately, and to correct or improve their performance as necessary, she adds. When this process is done over and over again, common sense and life experience tell us that the child will generally improve in performance.

But, she asks, do video games have to be violent to provide effective visual treatment?

My suspicion is that [visual improvement] is more likely caused by the action in certain games, not the violence, says Dr. Tea. The authors did not control for both variablesviolence and action. One gaming group experienced both variables and the other group experienced neither. How can the authors conclude which of the two variables was responsible for the difference in visual improvement?

Li R, Polat U, Makous W, Bavelier D. Enhancing the contrast sensitivity function through action video game training. Nat Neurosci 2009 May;12(5):549-51.