How exactly does one organize a study like this?

We started by sending a letter to our patients, asking for volunteers. We explained why we thought it might work. Of course, we warned of potential risks: The game was violent — they would have to wield a symbolic gun and blow away their “enemies” on a screen. It could increase aggression. The game could be addictive. Seven of our adult patients decided that the hope of better vision was worth the risk.

There was quite a bit of time involved. We tested their vision for five hours. Because there’s a learning curve to gaming, we supervised their play for another 10 hours. Then they went home with a loaded console and played for 10 hours a week, though never more than 2 hours at a time.

At the end of a month, we tested their vision again. They all showed some improvement on a number of tasks. Some were seeing better with their better eye or with their worse eye — or with both. Most improved in their ability to see direction of motion. They could see smaller details. They were able to see things that are in lower contrast. We were elated. This was a sign that the sensory brain can change in adults.

Why do you think this type of game was therapeutic?

Well, if you stepped back and asked what might be an effective therapy for visual defects, first-person shooter games have a lot of what’s needed. They require a person to monitor the whole field of vision, not just what is ahead of them. The player has to monitor everything, because the enemy could come from anywhere. The game is fast-paced. You can’t sit back because you will get shot dead. We know that the game changes neurochemicals. It causes an adrenaline rush. It also causes dopamine levels to rise in the brain. That potentially may make the brain more plastic.

The game we used has got what’s called vision for action. You have to look at the screen, make a decision and push the joystick in the right direction. So you are not only sensing the world, you are acting on it. We know that combining vision and the motor system is most likely to be effective. Now, not all games do this. Other researchers have tried a game called Tetris with people with normal vision. It’s not from the first-person perspective, and it is not fast-paced. They found it had no effect.

Do you have any insight on the science of why the games work?

One thing that might be happening is that they are changing the balance of excitation and inhibition in the inputs to neurons in the visual cortex. Video games could be actually rewiring the brain and allowing new connections to be formed. They could be unmasking connections that have always been there, but weren’t quite strong enough to be expressed. They might be helping the brain get more efficient at responding to small and weak visual signals. Or all three.

Some critics might complain that your study had only a small number of people in it — seven. How do you answer them?