dysTalk Dyslexia Overlays Using Coloured Lenses - Talks - dysTalk

About the speaker: John Stein is a professor of neuroscience in Oxford University Medical School. He is particularly interested in the auditory and visual perceptual impairments suffered by dyslexic children.

Further information about this Talk

Key Points Covered in This Talk:

• Dyslexia overlays and coloured filters are one of the ways that visual reading problems such as dyslexia are treated. In particular blue or yellow coloured filters.
  • Yellow Filters: These are useful because the magnocellular system is actually favoured by yellow light. The reason for this is that yellow filters give a higher contrast because the magnocells receive from two kinds of cones, so-called red and green cones, that together are best stimulated by yellow light. So if you give them yellow filters you are stimulating the magnocells preferentially. That gives the magnocells a boost and in the case of ones that are slightly impaired in poor readers this will help them to learn to read. Sometimes giving these yellow filters has a really dramatic effect, whereby a child who has been complaining that the words and letters have been moving around or are blurred can find things much clearer with yellow filters. On average, children who benefit from yellow filters will improve their reading by six months in a three month time period, therefore doubling their reading progress. This should be considered in the context that if such children are given no help to their vision then they tend to go backwards (in three months they might only progress one month). Therefore dyslexia overlays can have a significant impact.
  • Blue Filters: These ovlays are currenly being worked on but it is believed that these work in a different way because the blue filters stimulate a kind of cell in the retina (the eye) that is important for controlling your daily rythms. Deep in the brain there is a structure called the hypothalamus which has a clock in it. This is a genetic biochemical clock that needs to be synchronised to changing day-length. So there is a set of ganglion cells in the retina - cells in the retina that are sensitive to blue light, that then communicate, not with the conscious vision at all, but with the hypothalamus to synchronize the hypothalamic clock to existing day-length. That input is very sensitive to blue. Therefore, when blue filters are given these help children to synchronize his or her hypothalamic clock. This relates to magnocells as what happens is that during the day the magnocells are facilitated (their activity is enhanced) and at night they are damped down. Therefore if you enhance the clock you will enhance the magnocells during the day but you will damp them down at night. In addition to helping reading the blue glasses, particularly if worn in the morning will actually help sleeping. The children who benefit from blue often have problems with sleeping. Blue spectacles will improve sleeping patterns and they will be able to sleep at the right time and wake up at the right time. There is another benefit in that these same children often get migraineous headaches or stomach aches (called abdominal migraines). You give them the blue glasses and these go as well because they all depend upon this hypothalamic clock.