11May12_062Coloured Overlay Assessment and Meares-Irlen Syndrome

Some individuals with apparently normal eyesight, experience discomfort when viewing a page of print. Some report that the words appear to move, wobble or flicker while others say that the page appears too bright or the words are too close together. This condition is sometimes known as Meares-Irlen syndrome and is particularly prevalent in, although not exclusive to, people with dyslexia. Those affected by the condition may skip words or lines when reading. Others report eyestrain or headaches after reading.


There is now scientific research to show that both coloured filters (worn as spectacles) and coloured plastic sheets laid over text (known as overlays) can help some children to read. Coloured overlays are sheets of translucent or transparent coloured plastic that can be placed over a page of a book so as to colour the text beneath without interfering with its clarity.

Coloured overlays reduce the perceptual distortions of text that children sometimes describe. They enable some children to read text more fluently and with less discomfort and fewer headaches. It is important to assess the effects of a wide range of colours because individuals do not all benefit from the same colour.
Some people can experience distortions when they look at certain materials, particularly text. The distortions of text include blurring movement of letters, words doubling, shadowy lines, shapes or colours on the page, and flickering. These distortions are characteristic of a condition that some have called Meares-lrlen Syndrome, Irlen Syndrome or Scotopic Sensitivity Syndrome. Individuals with migraine are particularly susceptible to the distortions.
The people who benefit may be good readers, but more often they have difficulty reading. They usually suffer visual discomfort when reading and, when questioned, will often report perceptual distortions of the text. These distortions usually include apparent movement or blurring of the letters and words. Often there is a family history of migraine.

An optometrist will report ‘perfect eye sight’ when someone can see a letter chart without the need for spectacles, and when there are no problems of co-ordination between the eyes. The perceptual distortions may occur quite independently of any focusing problems, although they are often, but not always, associated with a minor problems of moving the eyes together and keeping the direction of gaze appropriately co-ordinated.
Many traits run in families and visual perceptual distortions are no exception. The genetic contribution is the subject of investigation.

It seems that people benefit most from colour if it is offered as soon as any reading difficulty is suspected, before the cycle of failure has begun. Many 7 year-olds appear to use coloured overlays for a year or two and then discard them as unnecessary. This may be because the acquired familiarity with text makes the distortion less distracting.

The optometrist will perform an examination with a pack of coloured overlays. and decide which colour, if any, reduces the reported distortions. Another way of assessing benefit is for the examiner to administer the Wilkins Rate of Reading Test .


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