A teacher in New Zealand, Olive Meares, was the first to provide a detailed written account of the spatial distortions affecting text being read by some individuals. Olive Meares also reported that the effects she cited could be reduced or eliminated by the use of coloured paper or by using coloured plastic overlays; the overlay is placed over the text to be read.
A psychologist working in California, Helen Irlen, wrote a paper describing symptoms similar to Olive Meares. Ms Irlen, named the effects as Scotopic Sensitivity or Irlen Syndrome. The syndrome was one in which reading is impeded by distortions of print. She reported that the distortions were positively effected if text was viewed through a coloured filter or overlay. Ms Irlen went further and established a protocol for screening for scotopic sensitivity and a system for dispensing coloured overlays as a result of the assessment.
There followed a period of time during which the scientific community discussed these findings with a great deal of skepticism. Prof. Wilkins and colleagues of Essex University were amongst the first to apply scientific rigor to the study of scotopic sensitivity or Meares-Irlen Syndrome, as it had become known. The Essex University team set up double blind placebo controlled trials and went on to establish a number of tools for screening for scotopic sensitivity and quantifying the effects of coloured overlays.
In the past, specialist assessors and educational psychologists with special training were able to assess and provide a coloured overlay for use when reading. Now this is not recommended, and if there are symptoms of visual stress then an in-depth optometry assessment should be sought. This should include assessment of binocular vision (accommodation and convergence) disorders, and visual stress, in addition to the standard sight-test comprising refraction and ocular health assessment.
If you or your child is experiencing visual effects such as text wobbling, moving, flickering, blocking out, underlining, halo effects, head aches and/or a feeling of over brightness, then it would be useful to have a specialist optometry assessment. You can ask if your usual optician is able to offer this service, or follow this link to BABO who have a map of behavioural optometrists.