What Is Meares-Irlen Syndrome?

In this blog post, we’ll explain more about Meares-Irlen syndrome, the symptoms, and how it links to neurological conditions like ADHD and Dyslexia.

Meares-Irlen Syndrome is a Visual Processing Disorder where people experience visual stress due to a problem with the perceptual part of the brain. First assumed as a subset of dyslexia, people with this condition see words as if they’re optical illusions ranging from blurry to rippled or shaky. 

In this piece, we’ll explain more about this condition, the symptoms, and how it links to neurological conditions like ADHD and Dyslexia.  

What Is Meares-Irlen Syndrome?

Mearles-Irlen Syndrome or Visual Stress is a neurologically based, visual-perceptual processing disorder. It affects the brain’s ability to process sight and perception which leads to problematic symptoms. The syndrome was first discovered in the 1980s by Helen Irlen, a US-based learning disabilities specialist. She discovered how readers experienced distorted words on a page that hindered their understanding of what they saw. The syndrome can also show up with other problems like: 

  • A slow or inefficient reading rate 
  • Attention deficit
  • Headaches and fatigue
  • Light sensitivity

Meares-Irlen Syndrome can run in families and be a lifelong condition. And it can affect up to 40% of poor readers. And while it was first thought to be a subset of dyslexia, it has a different cause and etiology. Studies suggest misdiagnosis in up to 33-46% of people with ADHD, dyslexia, and many other learning difficulties. 

If someone has Meares-Irlen Syndrome, they may find problems with the following: 

  • Lowered academic potential
  • Eye rubbing, eye tracking, and red eyes
  • Writing problems 
  • Depth perception 
  • Behavioral problems 
  • ADHD

What Is the Difference Between Meares-Irlen Syndrome and Irlen Syndrome?

American psychologist Helen Irlen first referred to perceptual problems in Visual Stress as Scotopic Sensitivity Syndrome. She drew this from a belief that the main difficulties in the brain came from an attempt to process light within a scotopic spectrum.

But the name was problematic due to a misinterpretation of the meaning. This confusion led to the renaming of the condition as Irlen Syndrome. But at the same time, New Zealand-based teacher Olive Mears identified the same symptoms through her research. This led to a new naming of Meares-Irlen Syndrome to reflect the work of two pioneering women. 

Is Meares-Irlen Syndrome a Disability?

Technically, Meares-Irlen Syndrome is not a disability. But there is a connection to neurodivergent conditions, specifically dyslexia. Research suggests almost 50% of people with dyslexia and a third of those with attention disorders may have Meares-Irlen Syndrome.

Meares-Irlen Syndrome Symptoms

As a spectrum disorder, someone with Meares-Irlen Syndrome can experience a wide range of symptoms. Often, principle symptoms affect tasks relating to fine vision and especially reading. The root causes aren’t fully understood but may be a result of light sensitivity. Symptoms can vary but those relating to reading may show up as: 

  • Blurred or merging letters
  • Letters jumping or spinning off the page
  • Faint or transparent words
  • Rippling and shaking effects
  • Skipping words or lines
  • Reading slowly or hesitantly
  • Swirling, wavy, transparent, and washed-out words 
  • Jumbled words that look like a puzzle
  • Faded words or seeing them where they’re not supposed to be
  • Losing place

More general, common symptoms can include:

  • Fatigue
  • Poor comprehension
  • Clumsiness, accident-prone, and bumping into things
  • Glare and strain from bright objects
  • Eye Strain
  • Lower performance level in sports
  • Concentration problems
  • Light sensitivity 
  • Headaches

It’s worth noting the similarities between symptoms found in Meares-Irlen Syndrome, dyslexia, and ADHD, despite being separate conditions. This leads to misdiagnosis and many individuals aren’t aware they have Meares-Irlen Syndrome. This may lead to diagnostic delays. 

What Is Visual Stress?

Visual Stress is a condition caused by visual-perceptual distortions when viewing text. Root causes aren’t defined but are thought to relate to an over-excitability of neurons in the visual cortex. Cells in the brain are working faster which causes visual disturbances when reading.

Studies suggest Visual Stress is more common among people with dyslexia, which raises important issues around the neuropsychological relationships between the conditions. The root causes of Visual Stress aren’t defined but may relate to the excitability of neurons in the visual cortex. 

Visual stress can be comorbid with many other conditions including dyslexia, dyspraxia, autism, ADHD, MS, and photosensitive epilepsy. 

Meares-Irlen Syndrome Treatment

Different treatments exist for Meares-Irlen Syndrome and their effectiveness varies for different people. Improvement rates may be low but are still worth considering to ease the effects. 

Many people respond well to the use of coloured lenses, known as Irlen, and to modified background colours and coloured overlays. 

Treatment should include an assessment with a licensed Orthoptist followed by a course of appropriate and specialised treatment. 

Treatment is often very effective for dyslexic children. A research paper showed a more than 20% improvement in reading speed for children with dyslexia when using a colour overlay in the Wilkins Rate Reading Test. This compares with children with high visual stress who showed between 5% and 10% improvement.   

Some things to consider when engaging in treatment for Meares-Irlen Syndrome include: 

  • Meares-Irlen Syndrome can inhibit a person’s ability to read both electronic and printed material. It’s a good idea to look for apps that offer a wide range of accessibility options including the ability to change the font and background colours.   
  • White backgrounds will be the least effective when it comes to reducing visual stress
  • Finding the right colours will vary from person to person and a student’s visual symptoms may reduce through a background colour such as yellow. 
  • The quality of light and whether it’s dull or bright makes a difference. Some learners prefer to avoid bright or fluorescent lights. 
  • Audio material can help to increase the understanding of text-based reading and reduce feelings of anxiety from visual stress. 

Links With Other Neurological Conditions

As a Visual Processing Disorder, Meares-Irlen Syndrome causes symptoms that mimic other neurological and neurodivergent conditions. The two most common neurodivergent conditions are ADHD and Dyslexia. 


Symptoms of Meares-Irlen Syndrome can mimic ADHD and misdiagnosis is common. It’s also possible to have both ADHD and Irlen Syndrome and it’s approprate to treat both conditions as separate. Some research suggests a good proportion of people diagnosed with ADHD only have Irlen Syndrome. And, once they’re treated for one condition they no longer have symptoms. 

As reported earlier, up to 46% of individuals with Irlen Syndrome may have misdiagnosed ADHD. 


Both Meares-Irlen Syndrome and dyslexia impact reading performance. But each one affects a different part of the brain. According to the BDA, dyslexia affects around 10% of the population. This compares to Meares-Irlen Syndrome which may impact up to 14% of the population. 

Neither conditions are visual problems but more differences in language and visual processing. Both appear to have a genetic cause and are spectrum disorders. 

In both conditions, individuals will also experience similar symptoms when reading. These may include fatigue and headaches. Some theories suggest Meares-Irlen Syndrome is very often comorbid with dyslexia, with ADHD and autism linked too. 

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