Individuals with Irlen Syndrome perceivethe printed page and/or their environment differently. Ifthey are severely affected, they must constantly make adaptationsor compensate. Individuals are often unaware of the extraenergy and effort they are putting into reading and perception.
Reading may be slow and inefficient, orthere may be poor comprehension, strain, or fatigue. IrlenSyndrome can also affect attention span, listening, energy level,motivation, work production, and mental health.
People with Irlen Syndrome are often seenas underachievers or as having behavioral, attitudinal, or motivationalproblems. Irlen Syndrome can also coexist with other learningproblems, such as attention deficit disorder, dyslexia, or autism.Treatment for Irlen Syndrome may lessen many of the symptoms ofthese disorders.
The following is a short excerpt from theIrlen Survey form, used to determine if screening for Irlen Syndromeis advisable. The full version (4 pages) can be downloaded here:Word Document PDFFile
If an individual answers yes to 3 or moreof the following questions, there is a good chance that they areaffected by Irlen Syndrome, and they should be tested by a qualifiedIrlen Screener. In the screening, he/she will find out for certainif they are affected, determine their level of severity, and learnabout treatment. More information about screening can befound at the bottom of this page.
Other signs of Irlen Syndrome include:
To see what the printed page can look like to someone with Irlen Syndrome, click here.
Although the exact cause of Irlen Syndromehas yet to be established, it has been shown to be a visual-perceptualproblem, most likely originating either in the retina of the eyeor in visual cortex in the brain. The following is a hypotheticalexplanation, based on current research into this syndrome.
In the visual system, there are two separate visualprocessing pathways, the Magnocellular, or Fast, and the Parvocellular,or Slow. The Fast pathway does not see colours, and is responsiblefor discerning movement, depth, and high contrast images. The Slow pathway determines colour, fine details and resolveslow contrast images. The Fast pathway is also responsiblefor inhibiting the slow pathway when the eyes are moved, so thatthe image of what was previously being looked at does not persist. It appears that in people with Irlen Syndrome, the Fast pathwayis disabled to some extent. This seems to affect the abilityof the Fast pathway to inhibit the Slow pathway, which in turnresults in images persisting when the eyes are moved. As a result,the brain perceives overlapping images. In severe cases, whenthe brain tries to interpret these images, it perceives imagesthat aren't there. The individual may "see" lettersmoving on the page, blurring, or forming strange patterns. Inless severe cases, the misperceptions do not occur or may be suppressed,but the brain expends more energy in processing the images thanis required by most people, resulting in headaches, eyestrain,and/or fatigue. These problems generally get worse the longera person tries to read, or do other visually intensive activities.
Bright lights, fluorescent lights, or glossypaper will often make the problems worse, as the extreme contrastwill increase the problem of persistent images. Irlen Syndromemanifests itself most strongly when reading words or music, becauseof the repetitive patterns on the page. When the eyes scan acrossthe page, the patterns of words on the page and persistent imageswill jumble in a manner that is difficult for the brain to interpretproperly. In the Irlen Method, the individual is assesed witha wide array of colour filters, singly and in combination, tofind the most suitable colour. The colour filters appearto act by blocking some of the light which would normally activatethe Slow visual pathway, in effect taking over the inhibitoryrole of the Fast pathway, and thus appear to reduce or eliminatethe persistent images. The filters stop the confusing signalsfrom being sent to the brain, and the individual will see thepage more normally and easily. This treatment may also behelpful to individuals who experience other related problems,such as faulty depth perception or night driving difficulties.