What is Irlen® Syndrome?

Irlen® Syndrome, also known as Scotopic Sensitivity System (SSS) is a visual perceptual problem. It is not an optical problem. It is a problem with how the nervous system encodes and decodes visual information. Academic and work performance, behaviour, attention, ability to sit still and concentration can all be affected.

Individuals with Irlen® syndrome see the printed page differently. Many do not realize their page is different. Irlen® syndrome prevents many people from reading effectively and efficiently.

 Until recently it has baffled educators and medical scientists because it has been undetected by standard visual and educational tests. Irlen® has a patented treatment method using specially formulated colored overlays, or spectral filters, worn as glasses or contact lenses, to reduce or eliminate perception difficulties.

Now there is much research showing why.  Read more.

See a three dimensional scan of the brain (PDF, 1.34MB) having Irlen® Syndrome, compared to a brain without Irlen® Syndrome

Take the self test.

Some of the symptoms of Irlen® syndrome include:

  • headaches
  • sleepiness when reading
  • skipping lines or words
  • losing place
  • poor comprehension
  • depth perception
  • light sensitivity
  • Words that shift, move, blur, become bright, or have haloes

Research now shows that Irlen® syndrome can help:

  • Research on Headaches and migraines. Read more.
  • Research on Traumatic Brain injuries. Read more.
  • Research on Autism and Asperger's syndrome. Read more.

    Individuals with Irlen® syndrome may:

    • Lose their place on the page easily
    • Skip words, lines or reread words or lines
    • Squint, open their eyes wide, rub their eyes or have red and watery eyes
    • Be able to see only a small portion of the page in focus. The rest may be blurry
    • See words that move, shift, wave, have haloes or ripple.
    • See a page that flashes, has spots, shimmers, flickers, or is too bright and glary
    • Move around or move the book to get it to focus
    • Display a short attention span because of eye strain or fatigue while reading
    • Experience nausea or even migraines because of movement on the page or in their world
    • Get a headache after reading for a while
    • Shade the page or move it to avoid glare
    • Be fidgety or restless while reading
    • Prefer to read in a dim light
    • Make errors when copying from the board
    • Misalign numbers in math problems
    • Have slow or choppy reading
    • Be unable to stay on task
    • Be an underachiever
    • Have problems with depth perception and difficulty with ball sports, and are sometimes labeled clumsy.


    Some have one symptom and some have many.

    It is important to realize that this syndrome is a perceptual dysfunction rather than a vision problem. Irlen® Syndrome, like any reading problem, can occur with someone who wears prescription glasses or even with someone who does not need them. Those who do not need corrective lenses will wear non-prescription filters with their specifically prescribed Irlen® spectral color in them.

    For those suffering from this syndrome, one or more of the colors that are part of the visual spectrum effect the speed and consistency of how the brain is able to interpret, not only the printed page, but everything around them.

    Studies show that Irlen® Syndrome affects to some degree approximately 12-15% of the general population, or over 17 million people in the U.S. In the population of those with learning problems, the incidence is about 45%.