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Visual Stress & Dyslexia

What is Visual Stress?
Many children and adults suffer from visual discomfort when reading. “Visual Stress” affects approximately 20% of the population and 5% are severely affected. This can affect reading fluency, concentration, comprehension and can cause eye strain/fatigue. Visual Stress is also known as “Meares-Irlen Syndrome” or “Scotopic Sensitivity Syndrome”. It can cause the following signs and symptoms:


  • moving closer to or away from pageblur
  • becoming restless
  • using a finger as a marker
  • skipping words and lines
  • rubbing the eyes and blinking excessively
  • low self esteem


  • movement of print
  • blurring of print
  • letters changing shape or size
  • letters fading or becoming darker
  • patterns appearing, sometimes describes as “worms” or “rivers” running through print
  • illusions of colour – blobs of colour on the page or colours surrounding letters or words
  • rapid tiring
  • headache or eyestrain

Symptoms of visual stress are not always immediately obvious. Many individuals who suffer with this condition believe the discomfort they feel when reading or the distortions they experience on the page are “normal” and experienced by everyone.

Who can Visual Stress affect?
Visual stress has been found to present itself many conditions including:

  • Dyslexia
  • Dyspraxia
  • Photosensitive Migraine
  • Photosensitive Epilepsy
  • Autism
  • ADHD
  • Head/Brain Injuries
  • Multiple Sclerosis

What causes Visual Stress?
The belief is that the stress is due to a hyper excitability of the neurons in the visual cortex, an area of the brain at the back of the head, which fire inappropriately. In other words these cells work quicker than normal, which causes the disturbances in the vision when reading.

How can Visual Stress be alleviated?
colorimetry1Colour has been found to be hugely beneficial in alleviating the symptoms caused by Visual Stress. This has been confirmed by the research carried out by Clinical Psychologist Professor Arnold Wilkins of the University of Essex and the Medical Research Council. Colour can be used in the form of coloured overlays or “Precision Tinted Lenses”.

In order to carry out this research Prof. Wilkins developed a calibrated instrument called the “Intuitive Colorimeter” to prescribe Precision Tinted Lenses. The Colorimeter measures three different parameters of colour; hue, saturation and brightness. By independently changing each parameter the precise tint required to alleviate visual stress can be determined. These details can then be sent to a specialist laboratory to produce the Precision Tinted Lenses, which can be incorporated into a pair of spectacles.

Dyslexia and Visual Stress
Dyslexia is a term used to describe various specific learning difficulties that affect the ability to learn to read and spell correctly. Visual Stress is NOT Dyslexia but can be particularly prevalent in Dyslexic individuals.
Many people with Dyslexia may also suffer with visual stress and can therefore be helped by colour. Equally there are a large percentage of children and indeed adults who are not identified as being Dyslexic but still suffer with these symptoms. The appropriate coloured overlay or Precision Tinted Lenses can also help this group of individuals.

What are coloured overlays?
Sheets of transparent coloured plastic that can be placed over written text. Used as a screening tool to determine if colour will be of benefit to the patient. They can alleviate some of the visual stress, making reading more comfortable. Each child will benefit from a different colour. The “Wilkins Rate of colorimetry3Reading Test” can be carried out to assess the benefit with the chosen coloured overlay.

What if overlays are helpful?
If the child continues to use the overlay through choice or the teacher/parent reports an improvement then it has most likely been beneficial. The overlay is usually given for a trial period of approx. 6 weeks. Spectacles with Precision Tinted Lenses can then be prescribed following an Intuitive Colorimetry assessment. These are more convenient/versatile as they can be used with white boards and computer screens. The Precision Tinted Lens is more accurate than the overlay as many more colour combinations are used and the tint will vary from person to person. The colour of the lens may differ from that of the initial overlay used.
The simple application of an overlay at an early stage could save years of anxiety and prevent the downward slide in confidence which occurs in most cases where children struggle to read. It is therefore important that overlays should not be reserved only for those pupils who have been “statemented” or identified as being in need of specific help. They should be available to any child who does not find reading comfortable.

Can adults be affected?
As we get older, Visual Stress can be less pronounced, but still there. In a lot of cases the condition goes undiagnosed and untreated until adult life. If you suffer with Migraines, Multiple Sclerosis or a Brain Injury you may also benefit from a Precision Tinted Lens.

Where can I get assessed for coloured lenses?
At Edmonds & Slatter Opticians we can assess you using the coloured overlays and the more specific Intuitive Colorimeter should a Precision Tinted Lens be required. One of our specially trained staff will conduct the assessment for you. It is advisable to have an annual colorimetry check as a change in the optimal colour can occur over time.

How to find out if colour will help…

  1. colorimetry2An eye examination with the optometrist to determine if a prescription is required. This is covered by the NHS if under 19 and in full time education.
  2. An overlay assessment which will help to determine whether colour is helpful or not. This may have already been carried out at school. A fee will apply for the assessment and chosen overlay.
  3. Intuitive Colorimetry if overlays are helping. The next step is to fine tune the colour to the patients individual needs and incorporate this into spectacles for convenience. A fee will apply for the assessment and the Precision Tinted Lenses.

Suffering from visual stress or dyslexia is no barrier to excelling in all aspects of life. Famous people who have/had dyslexia include actors Tom Cruise and Orlando Bloom, musicians Cher and John Lennon, artists Andy Warhol and Leonardo da Vinci, author Agatha Christie, prime minister Winston Churchill, head of the Virgin empire Richard Branson and the great Albert Einstein to name but a few…

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