Visual Factors in Reading Difficulties
by Sylvia Moody
 It has been estimated that about 40% of dyslexic readers have subtle visual problems – binocular instability and/or visual stress – which are not usually detected in routine eye tests. They can, however, be detected and treated by optometrists or orthoptists who specialise in vision and learning.
Binocular instability
This refers to a problem with the way the eyes are co-ordinated. It would not be apparent from simply looking at a person’s eyes, but could cause problems when that person was reading.
Symptoms
- tires quickly
- loses place on page
- misses out bits of text
- gets headaches
- becomes fidgety
- seems to be in own world
- reports blurred or double vision
- closes or covers one eye when reading
Treatment
Eye exercises or glasses.
 Visual stress
This is a problem caused by difficulties in seeing high-contrast detail and is thought to result from an ‘overloading’ of the visual part of the brain.
Symptoms
- eye strain
- headaches
- visual perceptual distortions:
- text appearing to change, move or swim on the page
- bright-coloured text or images
‘flashing’
- seeing shapes or patterns on the page
- white paper ‘glaring’
Treatment
Visual stress can be alleviated by the use of coloured filters or lenses, but different people need different colours. Consequently, the colour that a person needs should be determined with precision (since a very similar colour may not be helpful).
A well-researched system has been patented by the Medical Research Council. This involves Intuitive Overlays for screening and Intuitive Colorimetry for prescribing coloured filters or lenses. The use of these can increase reading speed threefold.
Where to get help
The symptoms of binocular instability can be hard to differentiate from the symptoms of visual stress, and some people can have both problems. People with reading or other learning difficulties should consult an eye-care practitioner who specialises in vision and learning.
A non-commercial list of practitioners in the UK with appropriate skills and equipment can be found at www.s4clp.org
Other articles by Sylvia Moody
Sequencing and Structure
Dyslexia, Dyspraxia, Dyscalculia: A Quick Guide
Dyslexia: A Psychotherapist's Guide
Dyslexia: An Emotional Account
Arranging A Diagnostic And Workplace Needs Assessment |
Stories
of particular
interest to dyslexic adults