Authors
Albert Le Floch and Guy Ropars

Left-right asymmetry of the Maxwell spot centroids in adults without and with dyslexia

publication date
18 October 2017
Category
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Abstract/Introduction

In human vision, the brain has to select one view of the world from our two eyes. However, the existence of a clear anatomical asymmetry providing an initial imbalance for normal neural development is still not understood. Using a so-called foveascope, we found that for a cohort of 30 normal adults, the two blue cone-free areas at the centre of the foveas are asymmetrical. The noise-stimulated afterimage dominant eye introduced here corresponds to the circular blue cone-free area, while the non-dominant eye corresponds to the diffuse and irregular elliptical outline. By contrast, we found that this asymmetry is absent or frustrated in a similar cohort of 30 adults with normal ocular status, but with dyslexia, i.e. with visual and phonological deficits. In this case, our results show that the two Maxwell centroid outlines are both circular but lead to an undetermined afterimage dominance with a coexistence of primary and mirror images. The interplay between the lack of asymmetry and the development in the neural maturation of the brain pathways suggests new implications in both fundamental and biomedical sciences.


Conclusion/Results

The noise-induced negative afterimage method enables us to determine the ocular dominance for an observer, which is correlated with the asymmetry of the outlines of the Maxwell spot centroids. Beyond genetics, the asymmetry between the two blue cone-free areas appears to be a necessary and fundamental condition for brain connectivity for a normal development. By contrast, the lack of asymmetry might be the biological and anatomical basis of reading and spelling disabilities in people with a normal ocular status but with dyslexia, perturbing the connectivity of different regions in the brain and inducing the observed common visual and phonological difficulties [54–56]. Our results suggest early anatomical diagnosis of dyslexia in young children and possible compensation for their potential lack of asymmetry, especially during the critical period. For adults, opportunities such as exploiting the small delays in the brain connections by using pulse-width modulation light-emitting diodes may provide novel strategies to overcome reading and other neurological difficulties.


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Also, he was better at listening. As a parent, we wanted learning to be fun for our Son, and vision therapy made this possible.


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Vision Therapy is well worth the expense, time and effort. Our son had a hard time focusing handwriting neatly. After vision therapy Seth could complete a task in half the time it previously took his abilities to focus and improved greatly and so did his handwriting.

Also, he was better at listening. As a parent you wanted learning to be fun for our son and vision therapy made this possible.


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Vision Therapy has given or son the tools he needs to be able to scan and read the written word more effectively and efficiently.

He love working with John and these working sessions give him the motivation to gladly work on his homework assignments.

It amazed us to see the difference in the tracking of his eyes and along a line of it's from the beginning to the end of the treatment.

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Prior to coming to the institute for vision development my son complained of daily headaches. Therapy has eliminated his headaches completely. I love knowing my son is able to learn pain-free for the rest of his life because of the work that has been done over just a few weeks in this office. He he absolutely loved coming that didn't even feel like going to a doctor or therapy. We are grateful for the relief he was able to find by coming here.

Thank you!


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Seems much less frustrated with life

Reads non-stop and fast

Spelling abilities have been hugely improved

Seems much more confident

Thank You!!!


Kelly O.

When we first came to the practice, my son did not have huge issues, but lots of small ones- trouble with reading, sports (hitting the baseball consistently), coordination, etc- that were not easily detectable,but when put together presented issues. The staff here were all very professional and loving towards him. While I was concerned in the reading, my son was concerned with the athletic side. Seeing improvement night off the bat gave him confidence that i have nor seen in him and made him want to not only Come to therapy, but also made him want to work hard. He has surpassed his grade level and above in reading and hit his first home run this year! Thank you!!!


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