Dyslexia, Visual Stress & Reading Difficulties

Dyslexia & Visual Stress (Meares-Irlen Syndrome)

Dyslexia is the most common learning disability with a prevalence of approximately 5% and is described as an unexpected problem in learning to read and spell in people who seem otherwise capable and intelligent.

Dyslexics may experience difficulty in understanding verbal language, in clearly expressing themselves either when speaking or writing. Some may confuse left and right or have problems with the concept of before and after, and some dyslexics may have difficulty with organisational and planning tasks.

Dyslexia is a lifelong problem, caused by some form of brain dysfunction although the mechanisms are not fully understood. A phonological processing deficit is generally thought to be a major factor in dyslexia and manifests as a problem associating letters with the constituent sounds of speech.

Visual problems are not the cause of dyslexia although they can contribute to reading difficulties and many dyslexics have visual deficits. Irlen, in 2005,  suggested that 46% of those with reading problems or learning disabilities have Meares-Irlen Syndrome (MIS) and 65% of dyslexics have the condition.

Many of the symptoms suffered by dyslexics are similar to those caused by Meares-Irlen syndrome - such as headaches when reading, blurring, moving text, double vision, or skipping words or entire lines.

The symptoms of Meares-Irlen Syndrome can also be indicative of visual problems, such as blurring or double vision. If symptoms of eyestrain and visual perception distortions are alleviated by using a coloured overlay or filter, then the patient is regarded as suffering from Meares-Irlen syndrome.

Dyslexics may well suffer from Meares-Irlen syndrome in addition to dyslexia,  compounding their reading difficulties. Treatment of the Meares-Irlen syndrome symptoms may not necessarily solve all of their reading problems.

The most common symptoms associated with Meares-Irlen syndrome are: 

  • glare from the page
  • headaches when reading
  • sore eyes when reading
  • movement/blurring of print


The most common signs are:

  • rubbing eyes
  • excessive blinking
  • poor concentration
  • inefficient reading
  • difficulty in keeping place 


There is now considerable evidence that, for reasons that are poorly understood, these symptoms are sometimes relieved by changing the background colour to the print. This can be achieved by placing a coloured filter over printed text (coloured overlay) or by wearing spectacles with tinted lenses. Computer users can be helped in the same way by changing the screen colours. The colour required to achieve optimum relief varies between individuals and may change over time.

As scientific and anecdotal evidence for the beneficial effects of colour has mounted, an increasing number of teachers, psychologists, optometrists, orthoptists and others have started screening for Meares-Irlen syndrome. The conventional method for screening involves manually presenting a range of coloured overlays/filters and asking the observer to report which colour is optimum in terms of reducing any symptoms. This process is somewhat tedious and prone to a variety of subject and examiner biases.

In a bid to improve the efficiency of the process, a team of scientists led by Professor David Thomson, developed the Colour Screener Xpert a computer based program which simulates the coloured overlay testing protocol. The Colour Screener Xpert program provides a quick and reliable indication of the optimum coloured overlay for individuals with Meares Irlen syndrome and this is the program used by Sightcare Opticians.

Using the Colour Screener Xpert program we can prescribe & advise on the use of:

  1. Coloured overlays.
  2. Tinted/coloured glasses.
  3. VDU Screen colour modification.


Please contact us for more information.

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