Scientists have
created video games that add an important element of fun to the repetitive
training needed to improve vision in people (including adults) with a lazy eye
and poor depth perception. The training tools, including a Pac-Man-style ‘cat
and mouse’ game and a ‘search for oddball’ game, have produced results in pilot
testing: Weak-eye vision improved to 20/20 and 20/50 in two adult research
participants with lazy eyes whose vision was 20/25 and 20/63, respectively,
before the training began. Unlike the common use of eye patches on dominant
eyes to make lazy eyes stronger, this type of testing uses a ‘push-pull’ method
by making both eyes work during the training. Patching is push-only training
because the dominant eye remains completely unused. With push-pull, both eyes
are stimulated but with the weaker eye exposed to more complex images that
create a stronger stimulus. In this way, both eyes are encouraged to interact
as they should, but the dominant eye's power in the relationship is suppressed.
This technique targets important pathways in the brain that must be active to
produce balanced vision.
Lazy eye, or
amblyopia, affects an estimated 2 to 3% of the population. The childhood
disorder results when the neural pathway from one eye to the brain does not
develop because the eye is sending blurry and/or incompatible images. This lack
of balance in the eyes typically leads to poor depth perception. Researchers
designed the push-pull training as a way to tap into brain networks responsible
for both inhibition and excitation signals that govern binocular vision. They
determined that the training can work not only for patients with a lazy eye,
but in people with normal vision who have more subtle eye dominance that
affects their depth perception. The improvements lasted for at least eight
months after the training was completed. The new computer games improve upon
the initial design by ensuring these pathways are adequately stimulated in each
eye, and even in lazy eyes caused by an eye turn. The games feature groups of
lines with differing orientation, and players wear red-green 3D glasses that
filter the images to each eye. The weak eye sees bordered disks that contain
vertical, horizontal or diagonal lines imposed against a background of those
same horizontal lines.
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