Coloured Overlays for Reading

Cerium Coloured Overlays Coloured Overlays Scientific research has shown that the use of coloured filters on spectacles or coloured overlays laid over text can help some children and adults to read better. The coloured overlays help to reduce the perceptual distortions of text which can sometimes be reported (Visual Stress or Mears Irlen Syndrome). This enables more fluent reading with less discomfort and fewer headaches. Approximately 5% of the population are severely affected by Visual Stress and 20% to a lesser degree.

Symptoms described may be as follows:

  • 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
  • oversensitivity to light

Or if you are observing a child you may notice:

  • moving closer to or away from page
  • becoming restless
  • using finger as a marker
  • skipping words and lines
  • rubbing eyes and blinking excessively
  • reluctance to read
  • short concentration span when reading

It is difficult to describe visual stress to a non-sufferer. You may recognise that sometimes when we look at someone wearing a very stripy shirt it may feel uncomfortable for us to look at and it may 'make our eyes go funny'. This effect can be seen by the many individuals with visual stress symptoms who look at print,as the lines of words on a page can appear to form a 'stripy pattern'.

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. That is until someone presents them with an appropriate colour and they realise that reading can become more comfortable and even enjoyable.

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.

The Assessment

Coloured Overlays A Cerium coloured overlay assessment is carried out only after a full eye examination. This is necessary to rule out other causes of the reading difficulty, for example long sightedness or eye muscle balance problems.

The assessment consists of allowing the individual to view text through different coloured acetates in a particular order. Their response is then recorded to the different colours, and through a process of elimination, the best colour or combination is determined. The reading speed and accuracy is recorded both with and without the identified overlay to measure whether there is any immediate effect. This assessment can take up to half an hour. The fee for the assessment is £85 and the overlays cost £12.50 each. This assessment can take up to half an hour and appointments are offered at our Caterham and Chandlers Ford branches.

Following the assessment if a benefit is felt by the patient or measured with the rate of reading test it is recommended that the overlay should be used without prompting. This is to eliminate any possibility of placebo effect to see if sustained use of colour improves reading fluency and accuracy or reduces previous symptoms.

If continued use of the overlay is found to be beneficial, it may be preferable to have Cerium Tinted glasses. We do not currently offer this service but we can arrange referral for further tests and supply of precision tinted glasses. The colour tint of the spectacles needed may be different to the overlay used.


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. If Visual Stress is identified and colour is used to alleviative some of the symptoms then other learning difficulties such as Dyslexia are easier to cope with.

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.

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 naturally like to look at books.

Why colour works

It is thought that this discomfort when looking at the print and hence the symptoms of Visual Stress in reading difficulties are also due to a hyperexcitability of neurones in the Visual Cortex. This means that some of the cells in the part of the brain which deals with processing of visual information work too fast and do not respond in the way they should.

We know that certain cells in the Visual Cortex are colour sensitive and therefore by placing a colour in front of the eye; the pattern of excitation can be changed. In other words the colour will help to slow and calm these cells therefore quietening the pattern and reducing the Visual Stress.

The colour needed to reduce the hyperexcitability is very precise and individual to each person.