Visual stress or Meares-Irlen Syndrome is a term used to describe visual discomfort and perceptual distortions in the printed text, suffered by many people who struggle to read.
Recent imaging studies suggest that the symptoms of this visual stress may be caused by a hyper-excitability of the visual cortex in the brain. The problem may also be linked to photophobia (being sensitive to bright lights) and migraine.
Some children and adults can experience visual tress and distortion when reading print which makes reading difficult and uncomfortable. It can occur in people who are good readers as well as those with reading difficulties and dyslexia. The condition is estimated to be present in about 40 % of poor readers and in 20 % of the general population in varying degrees.
Dyslexic individuals are more likely to experience visual stress than others, although visual stress is quite distinct from dyslexia and the phonological difficulties with which dyslexia is usually associated. Approximately 5-10% of the population is thought to have some degree of dyslexia, with boys being more affected than girls.
Optometrists do not diagnose dyslexia, but investigate visual problems that can contribute to reading difficulties.
Many thousands of individuals who find reading tiring and unpleasant, unknowingly experience visual stress. They have to work harder than their peers to achieve the same outcomes, often with extra tuition. Many could be helped by overlays or tinted lenses. It is therefore essential that every child who struggles to read is referred to a vision practitioner who can undertake a full eye examination and check for the presence of visual stress.
A diagnostic process has been designed that allows for the identification of visual stress, thereby distinguishing it from other barriers to reading.
Coloured overlays or colour tinted lenses can improve reading speed and accuracy. They can enable longer periods of reading free of discomfort. This is achieved by the simple selection of an optimum coloured overlay which is placed over the reading matter, or by choosing specific colour tinted spectacle lenses .
What are the possible symptoms?
All or some of the following may be present:
- Words move around when reading.
- Patterns can be seen in the print
- Blurring of letters or words.
- Leaving out words or lines.
- Using finger as a marker on the page.
- Tiring easily .
- Headaches or visual discomfort
- Frustration and low self-esteem
Colour can make a significant difference to the quality of life for migraine sufferers.Migraine is often associated with a sensitivity to glare, and most patients are photophobic during an attack. The glare sensitivity occurs in response to bright lights and bold geometric patterns, particularly those of stripes.
The sensitivity is associated with an abnormally strong response in the visual cortex of the brain.Research: In 2011 Professor Jie Huang, Michigan State University and his team, that included Professor Arnold Wilkins, published the first study, using brain imaging that showed a considerable reduction in visual cortical hyper activation in the brain when prescribed Precision Tinted Lenses.
The study concludes that normalisation of cortical activation in migraines with Precision Tinted Lenses, suggests a neurological basis for the therapeutic effect of the lenses in reducing cortical hyper activation.Other neurological conditions have been shown to benefit from the use of Precision Tinted Lenses. Research has shown that reading can, in some cases, improve significantly in Autistic spectrum individuals with the use of a precision colour. Acquired brain injury sufferers have also, anecdotally, shown benefits with a chosen colour. This work is ongoing.
Research has shown a link between binocular vision disorders and specific learning difficulties (particularly dyslexia). Problems such as incorrect focusing of the eye, poor muscle co-ordination or insufficient muscle strength all have an influence and these can be treated with simple exercises and spectacles.
For this reason, it is important that a thorough eye examination is done first.Although exercise and spectacles often dramatically reduce symptoms in many individuals who are struggling with reading and writing, those who are still having difficulties are often recommended to have either a Coloured Overlay Assessment, using the institute of Optometry (IOO) Coloured overlay Assessment or ReadEZ Screening assessment and possibly an eye movement assessment using the Bernell Developmental eye Movement Test (DEM).
If you have any concerns about yourself or your child you will not regret having a consultation. It could well be the start of a more productive and overall more enjoyable era of reading and learning.
Assessment varies according to age and ability. After conducting a full and thorough sight test, and screening for pattern glare, we may use either the IOO coloured overlay assessment, which is especially suitable for younger patients, or the ReadEZ System, which has a range of solutions including coloured overlays, coloured reading guides, coloured clip-ons, coloured spectacle lenses or virtual overlay software for computers.
We may also use the Bernell Developmental eye Movement Test (DEM).
The difference that can be seen with the use of coloured overlays can be phenomenal, with not only an increase in reading speeds but also an increase in confidence and concentration resulting in a new found enjoyment of reading and learning.
The appropriate colour for reducing symptoms varies from person to person and has to be chosen with great care and precision.
The overlays may only be needed for a period of months and on occasion the colour required may change, so it is a good idea to repeat the selection every six months.
The overlays are not suitable for written work, but if school children find an overlay useful for reading, they may prefer to write on coloured paper having a shade similar to that of the overlay.
If coloured overlays are used persistently for several months and are clearly beneficial, coloured spectacle lenses may be considered. Glasses are more convenient to use, and they can reduce eyestrain from stimuli other than books, such as whiteboards, VDU and reading music. The larger range of colour available with lenses may be helpful in obtaining the best effect.
The most effective colour for use with overlays is not always the same as that for use in spectacles, and must be assessed for separately.
Coloured lenses are not recommended for children younger than seven years of age due to difficulty of assessment.
Bernell Developmental Eye Movement (DEM) Test.
The eyes are required to move and then fixate repeatedly in a co-ordinated manner taking in information which the brain then has to translate to get meaning from text.
Problems with eye tracking can cause words to be missed out when reading and difficulty locating the next line of text.
We can assess eye tracking using the Bernell Developmental Eye Movement Test and prescribe exercises to improve this if necessary.