The assessment is performed in four stages:
The work we do with dyslexic adults and children is based on the work which was performed by Dr Bruce Evans, of the Institute of Optometry in London, and Arnold Wilkins, of the Department of Applied Psychology in Cambridge.
- Stage 1
- Stage 2
- Stage 3
- Stage 4
Stage 1 is a modification of a routine Eye Examination. We always start with this to ensure there are no obvious problems that have been missed in the past and, while Myopia does not appear to be correlated to dyslexia, Astigmatism and Hypermetropia certainly are.
Stage 2 of the assessment is to look in depth at the binocular vision status of the patient. There is definite evidence which shows binocular vision instability may well cause Asthenopia (a general discomfort of vision) which in turn may discourage a child from reading, and thus indirectly contribute to reading difficulties. In addition to this there is a correlation between either the over or under convergence of the eyes when reading, as well as eye movement problems.
Stage 3 is to look at the effect of coloured overlays on a person’s ability to read. The use of colour in either the form of overlays or spectacles is not new. In fact, there is anecdotal evidence going back to the 1930s where children in America were helped by tinted spectacles.
However, it was not until a controlled, double-blind study performed by Bruce Evans and Arnold Wilkins produced hard, scientific data, that it was proved specific colours can help certain patients to read better.
Stage 4 of the assessment follows approximately 6 weeks to 3 months after Stage 3 and if the patient is still using coloured overlays after this period of time, then we feel they are strong candidates for tinted spectacles. The instrument which we use to assess this is called an intuitive colorimeter and can give up to 120 000 variations of colour to ensure that we get the correct individual tint for the patient.
As this is such a complex and, in some cases, controversial subject, we do have a patient booklet which explains in more detail the principles we follow in the assessments. It is ideally suited for parents and teachers of dyslexic patients, and can be downloaded here