Visual Stress & Colorimetry

Coloured overlays
Tinted glasses with different colour

Visual Stress

At Scarborows Opticians, we have been treating adults and children with Visual Stress for over 20 years. Visual Stress (sometimes called ‘Meares-Irlen Syndrome’ or ‘Scotopic Sensitivity Syndrome’) generally reveals itself in the form of unpleasant visual symptoms when reading or carrying out close work, especially when done so for prolonged time.

What is visual stress?

Visual stress, a light sensitive condition that contributes to visual perceptual problems, impairs reading and can also be the cause of headaches, feelings of nausea or tiredness when reading.

People who suffer from this condition often find it difficult to focus on closely designed patterns, such as stripes or multi-patterns for instance. They may also suffer from problems of glare and feel uncomfortable in bright daylight or sunlight or under fluorescent lighting conditions.

Although present in 20 percent of the population to some extent, visual stress may not be recognised as a serious hindrance until it comes to coping with small repetitive black print on a white background, or with a volume of reading.

Many children who suffer from visual stress are often unaware that they see the page differently from others, until someone applies an appropriate coloured overlay (colorimetry) or prescribes precision tinted lenses. Then they often exclaim how words stop moving and how the page appears clear and still. Particularly with children, they don’t know what they see isn’t normal.

Some people do not recognise the severity of the problem, until it comes to a volume of reading at exam times for instance, when the inability to focus for a long period of time without becoming tired or suffering perceptual difficulties, suddenly arises.

The underlying photosensitive syndrome is also frequently involved in various neurological disorders that affect the visual cortex of the brain such as migraine, photosensitive epilepsy, autism, multiple sclerosis, head injury and stroke.

Coloured Lenses and Overlays

There is plenty of evidence that shows that Coloured Overlays and Coloured Spectacles can increase the speed of reading. This improvement sometimes may only be apparent after 10 minutes of reading or more but is more immediate when reading closely spaced text.

A Coloured overlay is a transparent sheet of coloured plastic that can be placed over a page or a book so as to colour the text without affecting its clarity. This colour reduces the perceptual distortions of text that people sometimes describe. They enable some people to read more fluently, with less discomfort and fewer symptoms of visual stress.

If any signs or symptoms of Visual Stress are present we would first recommend a full eye examination and overlay assessment. If an overlay is found to be helpful we would usually recommend trying it at home to ensure there is a continued benefit in your own environment.

If an overlay is beneficial the next step would be to book an Intuitive Colorimetry Test with our Dispensing Optician Henry. With our Intuitive Colourimeter, we can determine the precise colour and shade for spectacle lenses. Precision tinted spectacles are often more convenient than overlays for board work and when using the computer and writing.

Woman looking into pink window of the colorimeter


At Scarborows Opticians we have also had huge success in treating visual stress with Vista-Mesh lenses.


The Vista-Mesh lens has a micromesh filter built into the lens which acts in the same way as a Polarizing filter, elimating flicker, reducing glare and deflects EMI (electromagnetic interference) radiation. All of these things can cause problems for visual stress sufferers.

Vista-Mesh, if found to help, has the added benefit of being a much more inconspicuous option.

Mesh lenses for visual stress

Frequently Asked Questions (FAQs) about visual stress

All or some of the following symptoms may be present:

  • Words moving, blurring or going double
  • Letters changing size or shape
  • Patterns or halos of colour in text
  • Red, sore, watery eyes
  • Headaches when reading

Signs to look out for that may indicate visual stress:

  • Misreading text or reading words in the wrong order
  • Missing out words or whole lines of text
  • Losing the place on a page when reading
  • Tiring quickly when reading
  • Moving closer to or further away from the book
  • Moving the book around on the desk or fidgeting continuously
  • Using a finger as a marker on the page
  • Rubbing eyes or blinking frequently when reading
  • Poor comprehension of reading content

Some people may have all these symptoms but often people only suffer with one or two. It’s also harder for children to describe their symptoms or for them to know that what they’re seeing isn’t normal.

No. Dyslexia is a specific learning difficulty which causes the person with the condition to have problems with reading, writing, spelling as well as other things. People with dyslexia often suffer from visual stress and can benefit from overlays or tinted lenses. However, you can have visual stress but not be dyslexic.

We can diagnose and treat visual stress but not dyslexia. If a patient is diagnosed with visual stress and is struggling in other areas than just reading, we would advise a referral to an Educational Psychologist, as they are the only ones who can diagnose dyslexia.

The degree of improvement for each person differs. Some people experience improvements in reading age of one to two years very quickly. In others, the lenses may make it easier to read, but the improvement may be less dramatic because of other difficulties.