"Playing action video games resulted in an enhanced CSF and a shorter integration time for contrast sensitivity. To the best of our knowledge, this is the first report to identify a training regimen that improves performance over nearly the entire CSF in adults. These improvements were induced in central vision in young, healthy adults, supposedly at the prime of their visual abilities. This is of practical importance when driving at night or under degraded conditions, as well as during activities such as reading, which are known to correlate with CSF at 6 cycles per degree. More generally, our results establish that time spent in front of a computer screen is not necessarily detrimental to vision. The positive effect remained months and even years after training, indicating long-lasting gains.

[...] Video game training, therefore, may become a useful complement to eye-correction techniques that are routinely used in the clinic to improve eyesight."

Be: "Training consisted of one of two conditions: each
trainee played either experimental, action video games (action group played Unreal Tournament 2004 by Atari and Call of Duty 2 by Infinity Ward) or a control, non–action video game (control group played The Sims 2 by Electronic Arts)."

http://www.nature.com/neuro/journal/vaop/ncur....2296.html

(CSF = Contrast sensitivity, the ability to detect small increments in shades of gray on a uniform background, is one of the main limiting factors in a wide variety of visual tasks)