People with visual stress may experience one or several of the following:
- Blurred letters or words which go out of focus.
- Letters which move or present with back to front appearance or shimmering or shaking.
- Headaches from reading.
- Words or letters which break into two and appear as double.
- Find it easier to read large, widely spaced print, than small and crowded.
- Difficulty with tracking across the page.
- Upset by glare on the page or oversensitive to bright lights.
In some cases any of these symptoms can significantly affect reading ability. It can also make reading very tiring. Of course a child will not necessarily recognise what they see as a problem, as this is how they always see text.
If a child complains of a least one of these problems or has difficulty at school, they should be referred to an optometrist or orthoptist with expertise in this particular field. Many dyslexic people are sensitive to the glare of white backgrounds on a page, white board or computer screen. This can make the reading of text much harder.
- The use of cream or pastel coloured backgrounds can mitigate this difficulty as can coloured filters either as an overlay or as tinted reading glasses. – People with reading difficulties sometimes have a weakness in eye co-ordination or focussing and an specialist practitioner might recommend treating this with eye exercises or glasses. If these problems are present, they should be detected and treated before coloured filters are prescribed.
- Research in the UK and in Australia shows that people who need coloured filters, who are said to have visual stress, need to have exactly the right colour. Many optometrists and orthoptists use a special instrument, the Intuitive Colorimeter, to determine the exact colour that is necessary for coloured glasses.
- The choice of colour of text on white backgrounds can also affect clarity e.g. using red on a whiteboard can render the text almost invisible for some dyslexic students. For information on dyslexia friendly text see Dyslexia Style Guide.