Coloured Overlays for Reading

Research has shown that the use of coloured filters on spectacles or coloured overlays laid over text may help some children and adults who have symptoms of Visual Stress which can cause perceptual distortions of text. This may enable more fluent reading with less discomfort and fewer headaches.

Coloured Overlays Although the research in this area is controversial, Optometrists who use coloured lenses and overlays report that some patients find these interventions help to alleviate visual symptoms. Assessment is recommended to test whether colour may be helpful in an individual. 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'. When some people look at black and white stripes of specific width and spacing it can cause visual distortions and illusions. It is thought that when some people try to read the ‘stripy’ effect of the lines of print, it causes similar symptoms affecting their ability to read the text. This is known as Visual Stress.

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 can improve the appearance of the text to the visual stress sufferer rendering it easier 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 and appointments are offered at our Winchester and Chandlers Ford branches, the cost of this assessment can be found on our fees page.

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 common learning difficulty that can cause problems with reading, writing and spelling. It is a specific learning disability, which means it causes problems with certain abilities used / learning, such as reading and writing. Intelligence isn’t affected. It is estimated up to 1 in every 10 people in the UK has some degree of dyslexia.

Visual Stress is NOT the same as dyslexia. Visual Stress can occur in people with and without dyslexia. The use of colour can enhance the reading experience with or without dyslexia.

Studies indicate that prevalence of visual discomfort and disturbance in the general population, both children and adults, is high. It is at least as high in those who have specific learning difficulty. Visual stress or other vision problems do not cause dyslexia or specific learning difficulties. Treatment of visual difficulties does not treat learning difficulties. However, if people with specific learning difficulties such as dyslexia also have visual symptoms then these are likely to intensify their difficulty with learning from visual material.

If Visual Stress is identified and colour is found to alleviative some of the symptoms, then other learning difficulties may be easier to cope with. Although there is currently no strong evidence that tinted lenses are effective in improving visual function in patients with specific learning difficulties, Optometrists who practise in this area report that some patients find them helpful. Tinted lenses can be costly and the use of overlays to see if colour would be beneficial as a more economical option as a first step.

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.