For people who have amblyopia, or a lazy eye, just trying to see the world can be irritating. "When I'm using just my amblyopic eye, it feels almost like I'm holding my breath: my right eye wants to take over!!" wrote a woman named Sally on her blog. "It is the most uncomfortable sensation. There is a sense of urgency, like an itch you have to scratch; I have to open my other eye."
Most treatments for lazy eyes involved hours of staring at a boring screen or wearing an eye patch over the dominant eye for several (or all) hours of the day. And most people who have amblyopia, 2-3 percent of the population, hate wearing it.
But now researchers at Ohio State University have developed a Pac-Man-style videogame to help train lazy eyes in a more entertaining way.
Even more importantly, the treatment engages both eyes, which allows them to work together and allows people to perceive three dimensions better than before.
Teng Leng Ooi, a professor of optometry at Ohio State University, and her colleagues created a video game much like the arcade classic Pac-Man. Players wear red-green 3-D glasses, which allows the researchers to change what each eye sees on the screen.
The dominant eye, which would usually be covered by a patch, sees only horizontal lines. The weaker eye sees that same background of horizontal lines, but also sees circles superimposed on it that have lines of different orientations.
The result is a training method called push-pull, Ooi said, because the weak eye is pushed to work while the dominant eye is stimulated but suppressed. And this means that the eyes, little by little, can learn to work together.
These differently oriented disks are used in two games to strengthen the weaker eye. In one, the player controls a disk bearing an uncanny resemblance to Pac-Man to chase other disks with lines of similar orientation. In the other game, players have to match disks with rows based on the orientation of the lines in them. Researchers can make the games more difficult as players get better at them.
Ooi and her colleagues saw improvement in their subjects' vision for at least eight months after the training. But Ooi's team tested the game on only a few subjects, so more testing is needed to better evaluate how well the game works. But the subjects were in their 20s, which means there may be hope for adults with amblyopic eyes who currently have few treatment options.
Amblyopia is complicated to treat because it's not just the eyes that are the problem. Let's say one eye is sending a blurry or incomplete picture to the brain, but the other eye isn't. When a person is young and the brain is still developing and strengthening the most useful neural pathways, the brain will just ignore the information being sent by the weaker eye, which leads to a weaker pathway. So if the person's vision gets fixed later in life, the brain simply doesn't have the neural pathways to make use of it.
Luckily, brains can change over time. With the proper training, the brain can learn to incorporate the information from weaker eyes. The classic treatment for amblyopia has been an eye patch, which is worn over a child's dominant eye in order to strengthen the neural pathways for the weaker eye. But the process can be time-consuming, uncomfortable, really dull, and sometimes ineffective.
"The training we initially designed was quite boring. Participants had to keep their eyes still all the time and keep looking steadily at the same target, and it lasted for 1.5 hours," Ooi said. But the new game only last a few minutes at a time, she said, which keeps participants engaged.
It's not very common to use video games to treat amblyopia, but another team in Canada is using Tetris to make the eyes work better together. According to Robert Hess, a professor of ophthalmology at McGill University in Montreal, Canada, Ooi's push-pull method and his method of making the eyes work together better are similar in some ways.
"Usually the brain suppresses the information from the weaker eye, and with these methods you're trying to break your way through that suppression." he said. The subjects of Hess's Tetris method didn't see their vision regress over time, in Hess's case over several years. But the long term results remain to be seen as Ooi and her team t. "I think this [method], like ours and others, is moving toward approaching the problem as a binocular problem with a binocular solution," Hess said.
Correction: This story has been updated to correct errors in the description of the games as well as information about the study's participants.