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man suffering from visual stress



Visual stress is a term used to describe visual discomfort and perceptual distortions in the printed text, suffered by many people who struggle to read. It is estimated that up to 20% of dyslexic people experience visual stress and also the general population in varying degrees.

It is also sometimes called Meares-Irlen syndrome, scotopic sensitivity syndrome or just ‘Irlens’ the condition is linked to hyper-excitability in the brains visual cortex.


Colour has been known to make improvements to reading speed and accuracy. Colour overlays or tinted glasses or contact lenses may help enable longer periods of reading free of discomfort.


The following symptoms indicate you may be suffering from visual stress:

  • Tiring easily when reading

  • Letters changing shape or size

  • Halos of colour surrounding letters

  • Red, sore, watery eyes

  • Blurring of print

  • Patterns on print.


The first step of the Assessment would be to do a full eye examination is the first step in the Colorimetry assessment journey.  This is free when under 16 & when up to and including 18 whilst in full time education. Adults may be covered through the NHS or may have to pay privately. We always start with an eye examination to rule out any refractive error that might explain the symptoms.


Visual Stress cannot be corrected by prescription lenses and it can occur in people with 20/20 vision so if we found a refractive error we would want to be sure that this was not what was causing problems before moving on to assessing for colour.  We follow this with a visual stress assessment which is free to everyone.


If we identify visual stress we would suggest an appointment for an Overlay assessment to establish is colour is effective in reducing symptoms. If reading is the main problem we can run a Rate of Reading test which will give us a measure of improvement in reading accuracy and speed which is useful with younger sufferers.


Colour can also improve comprehension and retention, people often report that without their colour they have to read and re read a passage to make sense of it. If a simple colour is useful we can offer overlays, clipons and screen tinters for computer work.

using coloured overlays to help combat visual stress

If we feel that we can improve further by using a bespoke or precision tint then we would use our Colorimeter to run an assessment to establish the exact colour and saturation of colour that helps best. The colour prescribed in this way would be dispensed as tinted lenses in a pair of glasses, either with or without prescription.


The NHS will only fund the basic cost of a frame and lenses if there is also a refractive error. Otherwise unfortunately there is no NHS funding towards spectacles or overlays with both the cost of assessments and overlays/ lenses being paid for privately (although Higher education students can access help with funding through a DSA from student finance).

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