A guide to the role of visual problems in people who have difficulties reading.
Difficulties at school: is it dyslexia? People with specific learning difficulties have problems with certain skills at school. The most common type of specific learning difficulty is a difficulty with reading and spelling; this is often called dyslexia.
People with dyslexia may be highly intelligent in conversation, but have trouble with written language. Leonardo da Vinci and Albert Einstein are both believed to have had dyslexia.
The term dyslexia is usually reserved for a severe degree of reading difficulty. Dyslexia is diagnosed by an educational psychologist or qualified specialist teacher. Assessments that may lead to such a diagnosis can be arranged through your school or privately. Optometrists do not diagnose dyslexia, but they can detect visual problems that contribute to reading difficulties, including dyslexia, and so can help to treat the symptoms.
The term dyslexia is used throughout this page, but the visual problems that are described can also be present in children who have other difficulties at school, including dyspraxia. A person does not have to be diagnosed as having dyslexia in order to benefit from the tests outlined here.
Visual factors and school difficulties
Most experts agree that problems with sight are not usually a main cause of dyslexia. However, certain visual problems do occur more often in dyslexia and these may, in some cases, contribute to the reading difficulty. These visual problems would not normally be detected in a standard eye test. Two of the most common visual anomalies in dyslexia are poor or unstable co-ordination of the two eyes (binocular instability) and a reduced ability to focus at near. These visual problems can cause eyestrain, visual distortions or headaches. This may slow reading and discourage children from prolonged reading.
Not all people with dyslexia have these visual problems, but some have visual anomalies without realising it. People with a mild specific learning difficulty, perhaps not bad enough to be called dyslexia, can also have these visual problems. The visual problems can usually be treated with simple eye exercises. In some cases, spectacles may be required.
An optometrist is not able to diagnose dyslexia. However if reading difficulties are suspected it is sensible to start by investigating whether the visual function is normal.
Coloured Lenses and Learning
Some people with difficulties at school benefit from coloured filters. This has been called Meares-Irlen Syndrome, Visual Stress or Scotopic Sensitivity Syndrome. If our findings suggest that a person may benefit from colour we dispense a coloured overlay for them to try. If this is still found to be useful after a few weeks then a further appointment may be arranged for an assessment with a special piece of equipment, the Intuitive Colorimeter. This enables the precise tint for spectacle lenses to be determined. These have the advantage of not only helping reading but also writing and working from a white board.
For patients who are prescribed Precision Tinted lenses the exact colour of tint required can, like any other optical prescription, change over time. Therefore, we repeat the assessment with the Intuitive Colorimeter at appropriate intervals.
British Dyslexia Association is a dyslexia friendly society enabling all dyslexic people to reach their potential. www.bdadyslexia.org.uk
Dyslexia Action has local offices where psychologists and specially trained teachers can assess learning difficulties and help to overcome any problems. www.dyslexiaaction.org.uk