Vision, Dyslexia Not Linked: Study
Findings will advance understanding, treatment of the reading disorder, says expert
Further, children with dyslexia who received intensive tutoring in reading skills experienced a subsequent increase in visual system activity.
"When we ask children to learn to read, we are asking them to do something that is very difficult. Learning to read changes the brain," Eden said. "If you are a struggling reader because of your dyslexia, you don't have as much opportunity to read as the other kid in your class, and so your brain doesn't get the chance to change as much. The visual deficit is there, but our study allowed us to conclude it's there as a consequence of not having the same opportunity to read as children without dyslexia."
The new paper represents a key step forward for the field in that it narrows down the potential causes of dyslexia and helps shape future detection and treatment, said Laurie Cutting, associate professor of special education, psychology and radiology for the Peabody College of Education and Human Development at Vanderbilt University in Nashville, Tenn.
"Vision issues or involvement of visual processing have been reported and talked about for a long time with dyslexia, but so have issues involving language," Cutting said. "This paper begins to reconcile why these two types of findings exist, and provides some clues as to the future investigation of causal mechanisms."
Cutting said future research should focus on replicating these findings, and providing further explanation for the interplay between the visual and language centers of the brain.
"There's still the question of why this is a consequence of dyslexia," Cutting said of the visual impairments.
Eden said the new study also can be applied more broadly to other disorders in which differences in brain activity have been noted.
"We always have this chicken-and-egg problem," she said. "When we see a difference in a brain scan, we say, 'Was it there from the beginning and caused the problem, or is it the end product of an already existing problem?' In this case, consider that we've only been actively teaching children to read in the last 100 years. You are asking your brain to do something it wasn't designed to do, and having to do it induces all kinds of changes in the brain."