Eye Health

Amblyopia: Treating Lazy Eye with Tetris

David Mitchell - Friday, October 24, 2014

The classic addictive video game Tetris is being used in research to treat amblyopia, or "lazy eye," with optimistic initial results.

Amblyopia is the condition where one eye has reduced vision, not due to any structural problem with the eye, but due to a less than optimal connection between the eye and the visual centers in the brain.  

 Amblyopia typically occurs when the image in one eye is blurry but the other is clear.  The problem occurs because during a critical period of brain development, the brain ignores the eye with the blurry image, and only creates connections to the eye with the clear image.  Thus, the brain never learns to use the amblyopic eye during the critical period when it is capable of learning to use it.  
To simplify the explanation, I usually compare this to learning to use a TV remote.  Let's say I give you 2 televisions, with 2 different and very complicated remote controls, but with two different very detailed sets of instructions.  One TV has a sharp, clear image, and the other has constant static and a blurry picture.  
Let's say I leave you with these TVs for a year.  I would bet that in that period of time, you'd learn to use the remote to control the clear TV, but would probably not even pick up the instructions to try to learn to use the remote for the TV with the blurry picture.
Now, after a year, I show up and take both sets of instructions away.  Then I fix the picture on the blurry TV.  Does it matter? Probably not-- you likely won't be able to use the TV at this point anyway, because you never bothered to learn to use the remote (the connection) to that TV.  And you cant easily learn now, either, because the instructions are gone.
This is how it happens when a child has a high uncorrected prescription in one eye but not the other.  The brain only learns to use the "remote" to the good eye.  And after the neural plasticity (the "instruction book") is gone, the brain has a very difficult time learning to use the eye.  
So, unknowingly, the child has needed glasses for most of his life, and finally gets glasses.  The image in the poorer seeing eye is now clear, but the brain does not know how to use it. And so the brain must now be "taught" to use the amblyopic eye.
The brain maintains a fair ability to relearn to use an amblyopic eye when we are young-- under age 5 or 6 is ideal, and some improvement can be achieved up to age 11.  In some cases, improvement has been seen into adulthood, but these are very rare cases.
Patching of the good eye is the the mainstay of treatment for amblyopia.  By removing the ability of the brain to use the good eye, we can "force" the brain to learn to use the poorer seeing eye.  Pairing this patching with a specific regimen of vision therapy that includes visual resolution activities provides the best results.
Let's go back to the example with the TVs.  If I cut the power to the good TV, even for a few hours a day, you might be motivated to learn to use that other remote to see the now clear TV.  Maybe you even got a quick chance to read that other instruction book before I took it away.  You might be able to learn to use this remote over time.  Of course, if you read the instructions recently, you'll remember more and have a better chance of learning that remote.  If, however, we wait months or years, you'll have likely forgotten the instructions, and have less of a chance of making those connections.
That's similar to why time is of the essence when treating amblyopia with patching.  It must be done early and often, while the brain still "remembers" how to make the proper connections to the eye.

In a new study conducted by McGill University, researchers have gone one step further to attempt to treat amblyopia in older patients. Although improvement in amblyopia is traditionally thought to be unlikely in those over the age of eleven, adults were used in this new study.  Instead of simply blocking off one eye with a patch, the team created a special pair of goggles to work with the game of Tetris.  With the goggles on, the participants could see the blocks at the bottom of the screen with one eye, and the falling blocks with the other.  
This configuration forced the brain not only to use the amblyopic eye, but also forced it to use the good eye in conjunction with the amblyopic eye.  When compared to a group who patched while playing Tetris, the group with the goggles showed considerably more improvement in vision.  A major optimistic result from this study is that adults were the subjects, a subset of patients in which it  is conventionally thought that improvement of amblyopia is not possible.

Amblyopia: Treating Lazy Eye with Tetris