Wednesday, April 25, 2012

Study proves that vision problems interfere with learning to read and cause dyslexia

Researchers from the fields of optometry and neuroscience continue to be at the forefront of understanding the connection between vision and learning and the ways that brain-related visual problems such as visual information processing deficits affect reading and learning - and learning how to read. 

A new study published in the journal Current Biology in April 2012 has proven a causal connection between visual attention deficits and problems learning to read (dyslexia).  The study suggests that since visual attention deficits predict who will develop dyslexia, testing and treating these deficits in children may be a way to prevent dyslexia.  

Optometrists have been diagnosing and treating visual information processing deficits (visual attention is one component of visual information processing) for decades with vision therapy and have observed improved reading and learning in patients.  It's nice to have a study that objectively proves these clinical observations.

Here is a short summary of the study taken from Science Direct:

Reading is a unique, cognitive human skill crucial to life in modern societies, but, for about 10% of the children, learning to read is extremely difficult. They are affected by a neurodevelopmental disorder called dyslexia. Although impaired auditory and speech sound processing is widely assumed to characterize dyslexic individuals, emerging evidence suggests that dyslexia could arise from a more basic cross-modal letter-to-speech sound integration deficit . Letters have to be precisely selected from irrelevant and cluttering letters by rapid orienting of visual attention before the correct letter-to-speech sound integration applies. Here we ask whether prereading visual parietal-attention functioning may explain future reading emergence and development. The present 3 year longitudinal study shows that prereading attentional orienting—assessed by serial search performance and spatial cueing facilitation—captures future reading acquisition skills in grades 1 and 2 after controlling for age, nonverbal IQ, speech-sound processing, and nonalphabetic cross-modal mapping. Our findings provide the first evidence that visual spatial attention in preschoolers specifically predicts future reading acquisition, suggesting new approaches for early identification and efficient prevention of dyslexia.
Here are the highlights of the study:

► Poor readers show impaired visual search and spatial cueing when prereaders
► About 60% of poor readers displayed visual-attention deficit when prereaders
► Visual attention in preschoolers specifically predicts future reading acquisition
► Efficient visual-attention is crucial for learning to read independently of phonology

The study's findings highlight the need for parents to see a developmental optometrist who will do detailed testing for visual attention deficits.  If you don't live in the metro Vancouver area where our clinic is located, you can go to, which is the website of the College of Optometrists in Vision Development, to find a doctor near you. 

Not all health care professionals are trained to be aware of visual attention problems and how to diagnose and test for them.  In particular, one study from the neuroscience literature cautioned that an opthalmologists eye exam is focused on the physiology of the eye and not on brain-vision problems that are routinely diagnosed and treated by an optometrist. 

For example, in study published by Raymond et al. in the journal NeuroRehabilitationthe authors recommend the assessment of visual information processing should be done by an optometrist – not an ophthalmologist. The ophthalmologist, according to the authors, does not have the expertise to make the assessment. The study authors note that patients:

should be referred to a behavioral or neuro-optometrist. It was also noted that referrals made to an ophthalmologist may be insufficient, as they are primarily concerned with the health of the eye only, and ophthalmologists are mostly experienced with acute medical problems rather than rehabilitation issues. This assertion is supported by considering the typical components of an ophthalmologic exam, which may yield a lack of specificity, and/or provide information which is inadequately defined in terms of rehabilitation consequence. Trobe, Acosta, Kirscher and Trick identify a lack of measurement in areas of distance and near acuities, contrast sensitivity and confrontation, while Gianutsos and Matheson describe a need for greater quantification in terms of field gradations and boundaries, and binocularity conditions. A more thorough investigation is important for the rehabilitative efforts of all patients who demonstrate visual processing deficits.

There are other studies on the link between visual information processing deficits and learning problems. One example is a 2005 study by Goldstand et al. published in The American Journal of Occupational Therapy entitled "Vision, Visual-Information Processing, and Academic Performance Among Seventh-Grade Schoolchildren: A More Significant Relationship Than We Thought?" The researchers (consisting of professors of optometry and occupational therapy), set out to compare visual and visual-information processing skills between children with and without mild reading and academic problems and examine the incidence of visual deficits among them. They found that visual function significantly distinguishes between children with and without mild academic problems, as well as on visual-perception scores.

Another study published in Optometry and Vision Science in 2002 by Kulup et al. found that poor visual memory (one component of visual information processing) as significantly related to below-average reading decoding, math, and overall academic achievement (as measured by the Stanford Achievement Test) in second- through fourth-grade children, while controlling for age and verbal ability.