Lazy eye shifts brain wiring
Amblyopia, or ‘lazy eye’, has long been thought of as a permanent feature in adults. This facial feature, where one eye is often slightly askew, is seen in both children and adults. In children it can be treated with a high success rate, but what about in adults? This is exactly what UW-Madison psychology professor Bas Rokers wants to find out.
For high school sophomore and Wisconsin native Justin Gaal, having ‘lazy eye’ is a distant memory. Justin’s amblyopia was treated with a patch, one common form of treatment for lazy eye.
There is something different about a child’s brain that makes it easier to treat than an adult brain. At young ages the brain is still extremely plastic. This means it can be molded very easily. Think of clay when it’s brand new. It can be molded into virtually any shape. Once the clay gets older, it dries up and becomes solid.
This is how the brain works in adults. An adult brain changes very little compared to their children. The brain becomes less plastic after the critical period, which is from birth until six years when the visual system is still developing. The brain allows for changes so it can easily develop, but this also allows for disorders such as amblyopia.
“A better way to think about lazy eye is to call it ‘bully-eye’,” said Rokers, “it’s not that one of the eyes is lazy, the good eye is actually a bully and it’s suppressing the information from the weaker eye.”
A patch is used in young children, such as Justin, to remold the brain and change the structure. The patch goes over the strong eye for a period of time. “You’re basically trying to give the bully-eye a time-out, so it can’t do anything and it forces the lazy eye to become stronger.” However, treatments like a patch do not work with adults.
“One thing to realize [is that] it’s a deficit in processing visual information in the brain. The eye itself is perfectly fine,” Rokers said. In adults with amblyopia this treatment is ineffective because the brain cannot be molded. If the structure that is affected by amblyopia can be identified, it could be targeted in adults with less plastic brains.
Once targeted, researchers can attempt to make this portion of the brain more “plastic.” This would allow for highly successful treatment of lazy eye in adults.
It is important to understand what a normal functioning brain is doing in order to determine what is wrong in a brain with amblyopia. A typical week in the Rokers Vision Lab includes inviting patients to run tests. Not only does the lab work with patients affected by amblyopia, but also healthy individuals.
Rokers is currently a visiting professor at the Massachusetts Institute of Technology. He is using this opportunity away from UW to set up a multi-site collaboration and work with a range of patients both with and without amblyopia. “About 3% of kids have amblyopia so you want to try to have as many participants in your study as possible,” Rokers said, “one way of doing that is to recruit from multiple places at the same time.”
Weeden Bauman, a first year Medical student at the University of Wisconsin and previous undergraduate researcher in Rokers’ lab, worked with patients just like Justin to test their abilities despite having had amblyopia. “During summer, I moved on to helping with an experiment on people with amblyopia to see what’s happening in their brains while they do this.”
Bauman says that it was originally thought that people with lazy eye could not see 3-D images. His new research suggests that maybe the brain is capable of more. According to Bauman, “Individuals with amblyopia might be able to use motion cues to sense some 3-D depth perception.”
Rokers also tests the brain by placing a person in a virtual environment which simulates impossible situations. He looks to see how the brain responds to something it has never processed before, or is not physically possible. The results were surprising.
“It turns out the brain is smarter than we think it is,” Rokers said.
Justin was treated early enough for lazy eye and, today, has no symptoms. With recent research there may soon be hope for adults.
The brain is the most complicated part of the human. Understanding its structure and functioning could lead to not only the end of amblyopia, but also other brain deficits.
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