A screenshot from a Pac-Man-style game used as training tool for lazy eye and poor depth perception. (Ohio State University)
A screenshot from a Pac-Man-style game used as a training tool for lazy eye and poor depth perception. (Ohio State University)

In a novel use of video game playing, researchers at Ohio State have found a Pac-Man-like game, when played repetitively, can improve vision in both children and adults who have "lazy eye" or poor depth perception.

In the Pac-Man-style game, players wear red-green 3-D glasses that filter images to the right and left eyes. The lazy or weak eye sees two discs containing vertical, horizontal or diagonal lines superimposed on a background of horizontal lines. The dominant eye sees a screen of only horizontal lines. The player controls the larger, Pac-man-like disc and chases the smaller one. In another game, the player must match discs with rows based on the orientation of their lines.

Ten Leng Ooi, professor of optometry at Ohio State University, presented her research findings at last week's annual meeting of the Society for Neuroscience. Only a handful of test subjects were involved in the experimental training, but all saw weak-eye improvement to 20/20 vision or better and for a period of at least eight months.

Lazy eye, or amblyopia, affects between 2 and 3 percent of the U.S. population. The disorder usually occurs in infancy when the neural pathway between the brain and one eye (or sometimes both) fails to fully develop. Often the cause of lazy eye is strabismus, in which the eyes are misaligned or "crossed." To prevent double vision, the brain simply blocks the fuzzy images from one eye, thereby causing incomplete visual development. The result: lazy eye.

Most often the treatment in childhood for lazy eye is the use of an eye-patch over the dominant eye in order to try and strengthen the weaker one. But the researchers at Ohio State say a "push-pull" method, in which both eyes are encouraged to interact, is better. Instead of entirely disengaging the dominant eye, as with an eye patch, the normal eye's activity is only suppressed.

"We make sure the weak eye is seeing the contrasting images at all times," Ooi said at the meeting. "The strong eye has stimulation, but it is cortically suppressed. That is pull. The weak eye is pushed to work. And even if an eye is not stable, wherever your eyes are sharing vision, the corresponding retinal points are being stimulated. We think that makes our game design highly effective."

The games were played on laptops and lasted only a few minutes for each session. Researchers were able to add complexity to the games as participants became more familiar with them.

Pac-Man is widely considered to be a landmark in the history of video games, appearing in arcades in the early 1980s. It remains one of the highest-grossing video games of all time and is part of the Smithsonian's collection in Washington, D.C., as well as the Museum of Modern Art in New York City.