A Guide to Identifying Visual Stress

In recent years vision scientists have identified the condition of "visual stress" as contributing to reading difficulties in many children and adults.

The condition, which is related to light sensitivity in disorders such as migraine and epilepsy, can be responsible for distortions on the printed page, especially when black print contrasts sharply with the bright white background of the page.

Visual stress can be a major part of the problem in poor readers including those who are labelled 'dyslexic'. If visual stress can be identified and treated, any remaining difficulties become easier to deal with.

Visual stress can also cause headaches and eye-strain. It can do so not only in poor readers but also in those whose reading is otherwise normal.

Classic symptoms are:

  • "Words are moving around on the page"
  • "When I read I get a headache"
  • "The words are blurred"
  • "The page is very bright and I cannot see the words properly"
  • "Reading hurts my eyes"


Frustration and low self-esteem can occur in children who are under-achieving due to visual stress. Early diagnosis of the problem is essential. The longer it takes to identify and remedy visual stress the greater the loss of confidence that can result.

How Many Are Affected?

Approximately 5% of the population is adversely affected by visual stress, and 20% to a lesser degree. Since visual stress is common and easy to treat, it makes sense to took for visual stress in people who have difficulty reading.

A Solution?

Scientific research has shown that visual stress from reading can be reduced by colouring the page using spectral filters. The filters are either placed directly over the page (these are known as coloured overlays) or they are worn in spectacles (Precision Tints).

The colour is specific to each individual and has to be selected with precision. The best colour for use as overlays is unlikely to be the same as that for the spectacles. Coloured overlays can be used for screening and initial assesment, but individuals who find overlays helpful usually derive greater benefit from Precision Tints. A full eye examination is followed by testing with an instrument called the Intuitive Colorimeter. The instrument specifies the tint appropriate for glasses or contact tenses. Individuals using the appropriate tint can suddenly see more clearly and comfortably, in fact to them it can seem quite "magical". The tint permits a more fluent, efficient and comfortable reading, and is often useful not only for reading but more generally for reducing glare.

Signs and Symptoms to look out for ....

When Reading

  • Finds text uncomfortable to look at.
  • Closes eyes or looks away.
  • Rubs eyes.
  • Eyes become red or begin watering after minutes.
  • Frequently varies viewing position, restless.
  • Rapidly becomes tired.
  • Loses place easily, skips lines or words.

When writing

  • Has difficulty tracking across the page, work is poorly laid out.
  • Has difficulty when copying text from the board.

If asked, the individual may sometimes be aware of the following symptoms:

  • "the words move"; "the letters run into each other".
  • "the page is blurred (fuzzy)".
  • "the page is too bright".

Sightcare2000 can offer the full Visual Stress testing, overlays and lenses, please contact us on 0800 1696212 for more information.

"The Intuitive Calorimeter and Precision Tints have become a key instrument for optometrists who care for people with learning disabilities. " - Dr. Bruce Evans BSc PhD FCOptom DCLP FAAO Author of 'Dyslexia & Vision'.

'I never cease to be surprised by the remarkable specificity with which certain individuals choose a colour optimum for the clarity of text. The colour usually remains similar when you re-test these people weeks or months later If the colour differs from the chosen optimum by a small amount then reading fluency is adversely affected" - Professor Arnold Wilkins BSc DPhil CPsychol FBPsS Director Visual Perception Unit, Essex University.

Testing for visual stress using the Intuitive Colorimeter is usually carried out under the direction of qualified optometrists, using the guidelines set out by the - College of Optometrists. In some hospital units, testing is undertaken by orthoptists under the direction of a consultant ophthalmologist.

The Intuitive Colorimeter was designed and developed by scientists at the Medical Research Council Applied Psychology Unit, Cambridge, and is widely used throughout the U. K.