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 www.covd.org, 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 NeuroRehabilitation, the 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.

Vision therapy for visual attention skills significantly improves reading comprehension

The connection between vision and reading is well known to optometrists, all of whom study visual information processing (sometimes called visual skills) in optometry school along with treatments like vision therapy for deficiencies in visual imformation processing skills.

That body of knowledge is often not taught to other health professionals.  This makes it important to frequently talk about studies that prove the connection between visual skills and reading so that patients get the information they need to get the right help for themselves or their children who, although intelligent, have difficualty learning, reading or doing schoolwork efficiently. Researchers have commented that patients should be referred to an optometrist for assessment of visual information processing deficits because other professionals are likely to not test for them (see page 234 of this article from the journal NeuroReahbilitation).

Many people may be mistakenly diagnosed for learning disabilities or ADHD when the problem is actually a visual one.  At the very least, people who are suspected of ADHD or learning disabilities should see a developmental optometrist to be tested for visual information processing deficits to ensure that they are being treated for the right disorder.

One study on the connection between visual attention skills and reading was conducted by Harold A. Sloan, John Shelley-Tremblay, Anthony Ficarra, Michael Silverman, and Steven Larson and published in the Journal of Learning Disabilities in 2003.

In the study 15 moderately disabled readers received 12 hours of vision attention therapy. Significant improvement in reading comprehension and attention scores were seen in the group who received therapy, but not in the control group who received no therapy.

Here is the abstract that was published the the study:

This study quantified the influence of visual attention therapy on the reading comprehension of Grade 6 children with moderate reading disabilities (RD) in the absence of specific reading remediation. Thirty students with below-average reading scores were identified using standardized reading comprehension tests. Fifteen children were placed randomly in the experimental group and 15 in the control group. The Attention Battery of the Cognitive Assessment System was administered to all participants. The experimental group received 12 one-hour sessions of individually monitored, computer-based attention therapy programs; the control group received no therapy during their 12-week period. Each group was retested on attention and reading comprehension measures. In order to stimulate selective and sustained visual attention, the vision therapy stressed various aspects of arousal, activation, and vigilance. At the completion of attention therapy, the mean standard attention and reading comprehension scores of the experimental group had improved significantly. The control group, however, showed no significant improvement in reading comprehension scores after 12 weeks. Although uncertainties still exist, this investigation supports the notion that visual attention is malleable and that attention therapy has a significant effect on reading comprehension in this often neglected population.

The study is evidence of the connection between visual attention skills and reading ability as well as the efficacy of vision therapy in treating visual attention deficits and achieving a corresponding improvement in reading ability.

More visual symptoms means lower academic performance: study.

Undetected visual problems are one of the causes of academic difficulties in the classroom.

In a study published in 2006 in the journal, Optometry, researchers set out to determine whether there was an association between vision-related quality-of-life factors and academic performance.  To answer the question, the researchers used a 19-item questionnaire checklist developed by the College of Optometrists in Vision Development.

Ninety-one parents or guardians and their children in grades 3, 5 and 7 in a public school participated in the study. Both the parent and the student independently completed the vision questionnaire. The vision questionnaire scores of both groups were compared with the student’s results on the Stanford IX test scores for total reading, total math, total spelling, and total battery scores of the Stanford IX.

The researchers found that visual symptoms were found to be inversely correlated to academic performance.  This meant that the lower the academic score, the more symptoms were reported.

Source: Optometry - Journal of the American Optometric AssociationVolume 77, Issue 3 , Pages 116-123, March 2006