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Irlen Syndrome, or Scotopic Sensitivity Syndrome,was first identified by Educational Psychologist Helen Irlen whileshe was working with adult learners in the early 1980's. Until described in her book, Reading by the Colors (AveryPress, 1991), there was no explanation or treatment for this perceptualdisorder. Many people with this disorder were misdiagnosed asdyslexic or slow learners.  In 1991, Dr. Margaret S. Livingstoneof Harvard Medical School published research which offered a medicalexplanation for this disorder.

    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.

What are the signs of Irlen Syndrome?

    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.


* Do you skip words or lines while reading?
* Do you lose your place or reread lines?
* Does reading make you tired?
* Do you need to take frequent breaks while reading?
* Do you find yourself blinking or squinting when you read?
* Do your eyes hurt, or get watery or dry when reading?
* Do you prefer to read in dim light?
* Do you find you head moves closer to the page as you read?
* Do you use your finger or a marker to help you read?
* Does reading get harder the longer you do it?
* Do you get restless or fidgety when reading?
* Are you easily distracted when you read?
* Do you find it hard to remember what you have just read?
* Do you try to avoid reading?

Other signs of Irlen Syndrome include:


* Words appear blurry, or appear to shift on the page
* You are bothered by bright, glossy paper when reading
* You develop a headache or nausea during or after reading
* You have trouble copying from the board or produce unequal spacing when writing
* You have problems with depth perception, e.g. catching balls, determining distances when driving
*You have difficulty with headlights and streetlights at night

To see what the printed page can look like to someone with Irlen Syndrome, click here.

What is the Cause of Irlen Syndrome, and Whydo Colors Help?

    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.