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Visual Stress and Colorimetry


What is Visual Stress?

Visual Stress, (or Meares-Irlen Syndrome,) is a condition where distortions and symptoms of discomfort are experienced when reading passages of print and looking at certain striped patterns. Headaches and sore, watering eyes are common. Anyone can suffer from this, though it is frequently associated with the following conditions:

  • Dyslexia and Specific Reading Difficulties
  • Neurological conditions, such as Multiple Sclerosis and Photosensitive Migraine and Epilepsy.
  • Autism
  • Brain Injury

The symptoms of Visual Stress can be reduced by changing the background colour of the page using either overlays, which are transparent plastic sheets placed on a page of print, or coloured spectacle lenses.

The colour required is specific to each individual and may change over time.

How is the colour determined?

Because of the different modes of use, the colour needed for an overlay is unlikely to be the same as that required in a spectacle lens.

Overlay Assessment

Passages of print are viewed through overlays of different colours and colour combinations to determine the one that helps most. With the help of specialist computer software, improvement in reading speed and accuracy with the chosen colour can be measured to confirm the findings. Sometimes it is recommended by the Optometrist as part of a more detailed “Special Investigation” (Link to Dyslexia and Specific reading difficulties page)


Print is illuminated with light which can be varied in colour and intensity, enabling us to find the precise spectacle lens colour necessary to minimize Visual Stress.

Overlays v Coloured Lenses?


  • Overlays are useful for diagnosing Visual Stress as assessment is quicker and simpler than Colorimetry.
  • Overlays are less expensive.
  • Children can take an overlay home to make sure that colour makes a significant difference before considering whether to invest in coloured spectacles.
  • The optimum colour for spectacles can be assessed and supplied much more precisely than for overlays, with thousands of colour combinations available.
  • Overlays are generally used just for reading. Precision Tinted Spectacles are suitable in many more situations, such as writing, working from the board at school or college or when using a computer.

What should I do next?

If you think you or your child may benefit from the use of coloured overlays or spectacles please speak to your optometrist or contact the practice for advice. It is necessary first to have had a recent eye examination.

Some adults and children, often those with Dyslexia and Specific Reading Difficulties may be advised to book a “Special Investigation” which includes investigations into the co-ordination of the eye muscles as well the overlay assessment. (link to Dyslexia and specific reading difficulties page)

Most children will need to have had a successful trial with an appropriate coloured overlay before Colorimetry can be arranged. For adults with photosensitive migraine and epilepsy, MS and other neurological conditions, Colorimetry or Overlay appointments can normally be arranged following a comprehensive eye examination.

We look forward to hearing from you.

(Please note that Colorimetry is currently available only at our Houghton Regis Practice.)

At Brown and White we have been able to carry out Coloured Overlay assessments for Dyslexia for some years.

Many children and adults suffer from visual discomfort when reading. This can affect reading fluency, concentration and comprehension and can cause rapid fatigue. This Visual Stress can cause symptoms such as movement of print, “rivers” running through the print and headaches/eyestrain.

People who have persevered and found that overlays help them can now be assessed on a special machine to fine tune the colour required to be put into a spectacle lens, this machine is called the Intuitive Colorimeter and Brown and White has one at its Houghton Regis premises. For more information please download our leaflet.

CIMG2037 Intuituve-Coloimeter


Member of Society for Coloured Lens Prescribers