Vision, reading and dyslexia

Chapter 61 Vision, reading and dyslexia

I will outline current thinking about dyslexia, advise about what vision/ocular assessments should be carried out, and discuss the evidence linking dyslexia to the visual system.


A definition of the term dyslexia is emerging. This is due to be published in DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, American Psychiatric Association), and is outlined in Box 61.1.3

The major change (from the 1994 definition) is the removal of discrepancy between general cognitive ability and reading skills. While a discrepancy between achievement (in reading) and intellectual ability may still be present, it is now appreciated that all dyslexic children, irrespective of intellectual ability, have the same poor phonological skills.2 Furthermore, all groups demonstrate similar improvement as a result of evidence-based phonological interventions.4,5

An independent report, authored by Sir Jim Rose, formerly Her Majesty’s Inspector and Director of Inspection for the Office for Standards in Education (Ofsted), defined dyslexia as outlined in Box 61.2.6 Point 2 illustrates the three areas of phonological processing initially described by Wagner and Torgeson:7

Most dyslexic children demonstrate weakness in all three areas. Most educational psychologists agree that one standard deviation from the mean for that age signifies a significant weakness.

Dyslexia is common (5% of the population).8 It is distributed equally between the sexes,9,10 is familial, and persistent.

Dyslexia was originally a behavioral description (inaccurate or dysfluent word reading or spelling), but is now based on a defect at a cognitive level (poor phonological processing).8 Functional MRI findings demonstrate (in adults) activity in the left parietotemporal region during word analysis involving phonemes, and the left occipital temporal region for automatic rapid responding. The latter predominates in skilled reading.8 There is evidence that children with dyslexia rely on other areas (such as the inferior frontal gyrus and other right hemisphere sites) during reading, possibly as a result of compensatory processes. Anterior cortical areas, involved in articulation, may contribute in developing phoneme awareness (forming the words with the lips and tongue).

Comprehension is not a marker of dyslexia as it is currently defined. Comprehension may be poor as a result of an inability to read, so will often co-exist.

Jun 4, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Vision, reading and dyslexia

Full access? Get Clinical Tree

Get Clinical Tree app for offline access