Video games replace eye patch to treat lazy eye

The cat and mouse Pac-Man-style game found to help treat lazy eye

With video games having previously been found to improve decision making speeds and the brain's capacity to learn, scientists have now created challenging computer games with a fun element that significantly improved depth perception and binocular vision in people with a lazy eye. Unlike the traditional patch used to treat the condition, the video games encourage both eyes to work together.

The video games, created by Teng Leng Ooi, professor of optometry at Ohio State University, Zijiang He of the University of Louisville and Yong Su of Salus University in Pennsylvania, include a Pac-Man-style cat and mouse game and a "search for oddball" game that use a "push-pull" technique to force both eyes to work during training.

In a pilot test, the vision of two adult research participants with lazy eyes improved from 20/25 to 20/20 and 20/63 to 20/50, respectively. The improvements lasted for at least eight months after the completion of training.

Lazy eye (amblyopia) is a childhood disorder that affects 2 to 3 percent of the population. It occurs when nerve pathways between the brain and the eye don't develop properly because the eye is sending blurry and/or incompatible images.

As a result, the brain favors one eye and the weaker eye tends to wander. Eventually, the brain may ignore the signals received from the weaker – or lazy – eye, with this lack of balance in the eyes typically leading to poor depth perception. And the greater the imbalance is, the more depth perception is impaired.

The usual treatment involves an eye patch on the dominant eye in an effort to force the lazy eye to work. However, the stronger eye isn't used and when the patch is removed, the two eyes may not work together and the person is unable to get binocular, or 3D, vision.

The video games use a "push-pull" technique where, although both eyes interact, the weaker eye is exposed to more complex images, creating a stronger stimulus. In this way, the role of the dominant eye is suppressed and the lazy eye is encouraged to work harder.

The training targets important pathways in the brain responsible for both balanced vision and binocular vision. The video games are designed to stimulate these pathways in each eye, even in lazy eyes caused by an eye turn (a condition usually caused by poor eye muscle control where a person's eyes do not point to the same place at the same time).

The games feature groups of lines with differing orientation, and players wear red-green 3D glasses that filter the images to each eye. The dominant eye is stimulated with only a full screen of horizontal lines while the weak eye sees bordered disks that contain vertical, horizontal or diagonal lines imposed against a background of those same horizontal lines. The contrasting disks serve as the focal points of the games.

The weak eye sees the contrasting images at all times so is pushed to work, while the strong eye has stimulation but is suppressed. This is the "pull" aspect of the technique.

While the original games were, in Ooi's words, "quite boring" because participants had to look at the same target for one and a half hours, the new games are more enjoyable and challenging and only require participants to concentrate hard for a few minutes at a time. They can also be made more complicated or have shorter deadlines imposed as participants become more familiar with them.

The researchers say people with normal vision who have more subtle eye dominance that affects their depth perception can also benefit from the training.

The research was supported by the National Institutes of Health and was recently presented at Neuroscience 2014, the annual meeting of the Society for Neuroscience.

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