Irlen Syndrome: What Is It & Common Symptoms

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What is Irlen syndrome?

Irlen Syndrome, also referred to as Meares-Irlen Syndrome, Scotopic Sensitivity Syndrome (SSS) and Visual Stress, is not an optical impairment. Irlen Syndrome is a perceptual processing disorder that affects the brain’s ability to process visual information because of light sensitivity. This means that individuals with Irlen Syndrome, 15% of the general population, have issues when reading as printed pages usually appear like an optical illusion, words are seen distorted, falling off the page, pulsating, swirling around or blurry, bringing about diverse physical symptoms such as headaches, strain, fatigue, depth perception problems or inability to stay focused.

All in all, reading becomes a complex and exhausting task affecting reading comprehension as an individual doesn’t really understand what he or she is reading, resulting, therefore, in a barrier to learning and both professional and academic performance. In fact, around 46% of children with reading and learning issues are affected by Irlen Syndrome.

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What are the symptoms of Irlen syndrome?

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Irlen Syndrome is a spectrum disorder. This means that someone with Irlen Syndrome may experience a wide diversity of symptoms that can range from mild to severe. Some individuals are only able to see a few characters or words at once. Others may be able to read properly for a short period of time, but they get a bothersome headache after a while. In some cases, sleepiness or extreme fatigue may appear due to fluorescent lights, whereas most affected people with Irlen Syndrome have reading difficulties, and they need to read a paragraph over and over to get an understanding. So, as it happens with other neurological disorders, it can manifest itself differently for each individual.

The most common symptoms are:

  • Eye strain
  • Headaches
  • Fatigue
  • Poor performance in sports
  • Depth-perception problems
  • Slow or inefficient reading
  • Poor reading comprehension
  • Text and environment look different
  • Concentration problems
  • Light sensitivity
  • Difficulty with reading music
  • Difficulty with copying
  • Difficulty with maths

Hence, motivation and self-esteem usually result pretty badly as school marks do not reflect the effort.

We could classify symptoms into three groups:


  • Problems with distance judgement
  • Clumsiness
  • Difficulty catching things in movement, such as balls in sports
  • Difficulty while driving, especially at night, because of other vehicles’ lights


  • Misreading words
  • Problems when tracking from line to line
  • Skipping words and lines
  • Poor comprehension and concentration
  • Slow reading
  • Reading problems in dim lighting
  • Miscopying
  • Unequal letter and spacing size
  • Inconsistency spelling
  • Up/downhill writing
  • Words may vanish or appear unstable, blurry or moving


  • Fatigue and strain
  • Sleepiness, tiredness and problems staying focused
  • Restlessness, anxiety, irritability, dizziness or mood changing
  • Headaches and migraines
  • Watery and hurting eye feeling

Irlen Syndrome symptoms, dyslexia symptoms and ADHD symptoms are very similar, despite they are separate conditions, and, because of that, misdiagnosing is very common, but for those that experience Irlen Syndrome, the cause of symptoms is lighting. In addition, lots of individuals do not know they have Irlen Syndrome, and it is often mistaken for an optical impairment. All this may cause long diagnosing delays.

How is Irlen syndrome diagnosed?

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As it happens in other neurodiverse conditions, identifying symptoms and checking how they impact an individual’s daily life is crucial to determine the consistency of the syndrome.

If you think you have some of the symptoms above, you can get our online Irlen syndrome test, but remember this is not to diagnose the Irlen Syndrome yet to check if you have any traits. There are official Irlen Syndrome centres where you can ask for an assessment process.

Irlen Syndrome is not curable, so it means it does not go away. However, Irlen Syndrome can be treated and, by correcting it, an individual can see how his comprehension, motivation, self-esteem and academic performance improve. It is possible, thanks to coloured glasses/contact lenses and coloured filters/overlays, to be used on books pages or computer screens that filter the light and can immediately normalise the brain’s ability to process the information eyes see.

Some individuals affected with Irlen Syndrome also have some tricks to improve their symptoms, such as using dimmer lighting, using incandescent light instead of fluorescent light, using coloured papers instead of white sheets of paper, adjusting the computer monitor brightness, using a coloured background on the computer’s screen or even wearing a black cap to minimise the lighting reflection.

Webinar: Do I Have Meares-Irlen Syndrome?

Nat Hawley, our Head of Community, has hosted a webinar that explains the symptoms of Irlen Syndrome. The webinar is not intended to diagnose Irlen syndrome. Only a qualified medical professional can make a diagnosis.

Blog Author

Natalia Herrero López