Playing Medal of Honor could improve eyesight, even among people with conditions that appear difficult to treat.

That’s the conclusion of psychologist Daphne Maurer who carried out a study of six adults who had been born with cataracts, a clouding in the eye lens that can block out most subtle detail. Each of the subjects had the cataracts removed as a child, but had been left with poor vision. That’s because while they were growing as babies, their visual cortex didn’t develop as well as in babies who didn’t have any problems with their eyes.

As a result, the adults now had poor vision that was caused by the brain rather than the eyes themselves. That left Maurer investigating whether the brain could be “retrained” to take better advantage of the now-working eyes.

The subjects were asked to play the game for 40 hours over the course of a month and then had their sight retested. Maurer says that five of the six showed a “substantial” improvement, specifically in being able to cope with low contrast, and in being able to distinguish more detail both in static and moving objects. Of the full range of tests for specific elements of eyesight, the patients showed improvement in around two-thirds of the elements. As a more general quantifiable measure, she likened it to being able to distinguish two additional lines on an eye chart.

The findings are very much preliminary. Maurer says that she expects the effects to last, but that will need to be tracked, and she notes that a more formal and larger-scale clinical trial would be needed before doctors could consider using the technique.

Maurer says she is now hoping to find a way to replicate the success of this “treatment” but with a non-violent game. It will be interesting to see if this is possible, or whether the adrenaline involved in playing a character “under fire” is playing an important role in increasing focus.