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17 Green Lane, Ashton on Mersey, Sale, Cheshire, M33 5PN

Colorimetry & Overlay

We offer an examination to investigate the symptoms and relief of Visual Stress (Meares-Irlen syndrome) in children and adults. Many children and adults suffer from visual discomfort when reading. This can affect reading fluency, concentration and comprehension and cause fatigue.

Visual Stress is a term used to describe visual discomfort and perceptual distortions in printed text often experienced by people who struggle to read. The condition is estimated to affect approximately 30 % of poor readers and 10 % of the general population to a significant degree. People with visual stress describe symptoms such as:

  • Words moving around the page.
  • Blurring of print
  • Letters changing size or shape
  • Patterns in the print (sometimes described as rivers or worms)
  • Tiring easily whilst reading

Signs of visual stress are some or all of the following:

  • Moving closer to or further away from the book
  • Moving the book around
  • Fidgeting continuously
  • Using finger as a marker on the page
  • Skipping words or lines
  • Frequently re-reading the same line
  • Rubbing eyes or blinking frequently when reading
  • Poor comprehension of reading content
  • Frustration and low self-esteem

These signs and symptoms can occur despite the person considered to have normal vision even after an eye test. One current scientific explanation for the occurrence of visual stress is the over excitation of the part of the brain called the visual cortex, this over excitation may be reduced when looking through a precise individual colour.

Visual Stress and Dyslexia

Visual stress is NOT the same as dyslexia but is more common in those who are dyslexic. People who fail to read because of visual stress are frequently mis-diagnosed as dyslexic. For this reason it is important that the existence of visual stress is identified at an early stage. Once visual stress has been alleviated, any remaining problems are easier to solve.

Photosensitive Migraine and other conditions

Migraine attacks have many triggers, including stress and particular foods and hormones. About 40% of migraine attacks may be visually induced by flickering lights, patterns or reading. These attacks may be reduced by coloured filters. Research in the U.S. by a team of neuroscientists, using brain-imaging techniques, has shown that a suppression of over excitability in the visual cortex occurs in migraine sufferers when individually selected precision tinted lenses are worn. The lenses used in the study were selected using the Intuitive Colorimeter.

Symptoms of other neurological conditions such as Autism, MS, ME and Parkinson’s have been shown to reduce when looking through coloured filters.

Coloured filters can help

Visual Stress can be reduced by the use of coloured filters which is usually in the form of a coloured overlay (transparent coloured sheet) placed over text or precision tinted spectacle lenses. Overlays are widely used by teachers in schools throughout the UK. The reduction occurs only when a specific colour is determined to suit the individual.

The selection of such a specific colour is firstly carried out at a overlay assessment. If after trying a coloured overlay at home, work or school is found to be beneficial then a more precise colour is determined with the Cerium Intuitive Colorimeter. This colour is then applied to spectacle lenses in the form a precision tint. This is often found be more effective at helping the symptoms than an overlay. In addition, it is more convenient for the person to look through spectacles than an overlay, for example, when reading from a board at school or for writing as well as reading.

Precision tinted lenses frequently result in reading that is more fluent and comfortable. Some lens wearers enjoy significant improvement in both reading rate and accuracy. The degree of improvement differs: some children experience improvements in reading age of one – two years within a few weeks of acquiring the lenses.  In others the lenses may offer greater comfort when reading, but the reading improvement may be less dramatic because of other reading difficulty.

A full eye examination is necessary before prescribing overlays or precision tinted lenses in order to eliminate the possibility of a focusing or eye muscle problem. Please contact the practice for more information about our colorimetry service (overlay assessments and assessments with the the Cerium Intuitive Colorimeter) and the fees involved as currently colorimetry investigations overlays and precision tinted lenses are not funded by the NHS.

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