Researchers at Universities of Bristol and Newcastle have suggested through a first of its kind study that the possible link between vision problems and dyslexia are unlikely and that bodies in the UK should produce evidence-based guidelines for the management of children with dyslexia.
In the study, the team of researchers from the two universities looked at results of comprehensive eye tests in 5,822 participants in Children of the 90s – a large population-based study in the southwest of England. Researchers found that out of all the children 172 (three per cent) had severe dyslexia while 479 (eight per cent) suffered from moderate dyslexia.
The researchers then compared the test results of the children with severe dyslexia with the other 5,650 children of the same age in Children of the 90s who didn’t have dyslexia. The analysis revealed that majority of the dyslexic children had perfect vision on each of the tests. For example, more than eight in ten (84 per cent) of the dyslexic children fused (combined) information from each eye perfectly whilst 16 per cent did not, but importantly one in ten (11 per cent) of non-dyslexic children didn’t fuse either.
Researchers also found that 3D vision was excellent in more than eight in ten (83 per cent) of the dyslexic children and was only seriously reduced in two dyslexic children and in another 13 children who were not dyslexic.
Dr Cathy Williams, a paediatric ophthalmologist and the study’s lead author, said that the findings of their study provide a rather “bigger picture” and show us that vision problems are rare in dyslexic children.
Researchers did find dyslexic children with few vision impairments, but they also occurred in their non-dyslexic classmates indicating that there is possibly no link between eyesight issues and dyslexia.
Dr Williams added that their study, contrary to beliefs of some practitioners, shows that majority of dyslexic children have entirely normal vision.
The lead author suggested that families whose dyslexic children are being treated for eyesight problems should ask questions such as what visual impairment is actually being treated? And what are the factors through which the effectiveness of such a treatment will be tested.
She further added that families should start asking for evidence that such a treatment will help their child with dyslexia?
These are the questions that will help families decide whether any sight treatment offered is likely to help their child’s dyslexia.
Dr Alexandra Creavin, one of the co-authors from Bristol’s School of Social and Community Medicine, added that their findings reassure families that their child’s sight is very unlikely to be affecting their reading ability (assuming the need for glasses has been ruled out) and so they can pursue other options for supporting their child.
“Fortunately there are treatments and training programmes to help children with dyslexia that do have a good evidence base, including training in phonics (speech sounds)”, Creavin added.
Creavin hopes that national bodies like NICE in the UK will start looking at creating evidence-based guidelines for the management of children with dyslexia and that charities and support groups will signpost families to the best sources of support for their children and present a balanced view of all the evidence.
What do others say?
The findings of the study fall in line with opinions of organisations, institutes and experts of dyslexia. According to Minnesota Vision Therapy Center, many symptoms of visual disorders mimic symptoms of dyslexia, ADD and ADHD and most of the children and adults who are carrying the label of dyslexic, ADD or ADHD actually have functional vision problems. Dyslexia type symptoms can occur when there are eye teaming, eye tracking and perceptual problems that can cause words, letters and numbers to appear to move or jump on a page. With many families mistakenly think that they or their children have dyslexia because they can see 20/20 with or without corrective lenses and still have trouble reversing words, letters and numbers. Many of these same children and adults have never been tested for or told that they may have a vision disorder. There are cases where both problems are present. True dyslexia can still be present in rare cases after vision disorders are resolved, but in many cases what was thought of as dyslexic symptoms disappear once the eye teaming, tracking and perceptual vision skills are strengthened.
According to a study published in 2009 entitled “Learning Disabilities, Dyslexia, and Vision“, there is no adequate scientific evidence to support the view that subtle eye or visual problems cause learning disabilities. Furthermore, the evidence does not support the concept that vision therapy or tinted lenses or filters are effective, directly or indirectly, in the treatment of learning disabilities. Thus, the claim that vision therapy improves visual efficiency cannot be substantiated. Diagnostic and treatment approaches that lack scientific evidence of efficacy are not endorsed or recommended.
