A year and a half ago I wrote a blog piece here on a marvelous book regarding the Visual Aspects of Dyslexia. At the end of the piece I welcomed other professionals to broaden their thoughts and actions behind the false dichotomy of reading difficulties being “either” a phonetic problem or a visual problem. Thanks to Linda Sanet for sharing the following review of Visual Aspects of Dyslexia published in the September/October 2013 issue of The Educational Therapist – the official journal of the Association of Educational Therapists. It is such a powerful endorsement of the potential role of vision by an educational professional that I would do it an injustice by anything other than reproducing it in its entirety.
John Stein & Zoe Kapoula, editors. Oxford, UK: Oxford University Press, 2012 224 pages; $79.95
After working for more than a year to remediate the reading problems of a young client with dyslexia, I discovered that he was seeing double. One day I mentioned to him that if I read when my eyes were tired, the lines sometimes pulled apart into two lines, making me work harder to keep them together and in focus. I asked, “Does this ever happen to you?” and he said, “All the time.” Verbally gifted, he could describe exactly what he was seeing—one line of text above the other, with letters and words reversed in one line. Covering one eye, then the other, he said, “My right eye sees ‘Tom’ and my left eye sees ‘moT’ underneath.” It never occurred to him that we didn’t all see what he saw. When we asked why he didn’t tell us, he said, “You never asked.” Clearly, there are questions about vision that educational therapists need to ask.
In 2009 the American Academy of Pediatrics and other professional organizations published a Joint Statement— Learning Disabilities, Dyslexia, and Vision stating in both the abstract and conclusion that “Diagnostic and treatment approaches that lack scientific evidence of efficacy, including eye exercises, behavioral vision therapy, or special tinted filters or lenses, are not endorsed and should not be recommended” (American Academy of Pediatrics, et al., 2009 ). This joint statement has carried great weight for denying the value of vision therapy in the United States, even though the text of the article between the abstract and conclusion points out that “routine pediatric vision screening is not designed to detect near-vision problems” that can interfere with reading for which the authors do recommend treatment. An article in The New York Times, “Concocting a Cure for Kids With Issues” (Warner, 2010), made the criticism of vision therapy widely available, portraying that criticism as the professional stance and acceptance of vision therapy as coming from desperate parents. It is clear that some therapies did not have sufficient research evidence of effectiveness before they became commonly applied. Perhaps it was a matter of competing theories between developmental optometrists and ophthalmologists. However, a great deal of scientific evidence about dyslexia, vision, and vision therapy has now accumulated and should be considered.
In the United States, the consensus in the reading community describes dyslexia as a core deficit in phonological awareness and phonological memory. However, in Europe and Australia, the effects of vision problems have received more attention.
Visual Aspects of Dyslexia gives Americans a chance to catch up on the extensive research. Eleven thoroughly documented chapters by European and Australian scientists present the evidence and clinical significance of vision for reading. Only one author (chapter 10 by Vidyasagar) argues that visual deficits are the fundamental deficits in dyslexia. Most of the authors simply argue that since seeing the letters and words must precede successful use of phonological strategies, vision must be considered.
The mechanics of typical as well as dyslexic reading are extensively explained in this book. It is generally accepted now (Dehaene, 2009) that we co-opt brain areas that evolved for object recognition in order to recognize graphemes and words. A deer in the field is still a deer, whether facing left or right. Both skilled readers and readers with dyslexia must learn to overcome mirror invariance in order to read text by seeing words from left to right (in English). Even though we read in one direction, we use the same muscle systems to move our eyes across a line of text that we use to watch the deer run across the field. Both involve brain systems designed for perceiving motion, a spatial-temporal perception challenge. To do this, both eyes must focus on the same spot at the same time, and they must move in synchrony to the next spot. Visual acuity (e.g., 20/20 vision) is a measure of only the fixed focus, not the synchronized movement required for refocusing. One line of text may involve many re-focusing events, though we are mostly unaware of this physical proficiency. It should not be surprising that the ability to do this develops with age. In normal development, binocular convergence does not reach an adult level of coordination until about age 12 (chapter 3 by Kapoula). Consider in this context how dramatically font size in assigned reading drops at about this same time. Readers with dyslexia tend to have slower and less efficient binocular convergence, more frequent reverse saccades (eye jumps in the wrong direction), and have difficulty tracking to the next line of text. Stein (chapter 11, p. 175) reports “….we find that over 50% of the children we see in our clinics have significant visual problems and that these often contribute to their phonological ones.” Fortunately, our amazing brain plasticity allows training. With adequate diagnosis and appropriate eye training, and given sufficient maturity of brain development, vision problems can be remediated, fostering better academic outcomes.
Reading can also be difficult for people who do not have dyslexia. Our eyes developed to see the natural world around us, but un-natural contrast and motion present varying levels of difficulty. Consider the flicker of fluorescent lights or repeating patterns that trigger seizures in some epileptics or migraines in susceptible people. It turns out that printed text often fits the parameters of spacing, pattern, and contrast that lead to visual stress (chapter 4 by Wilkins; chapter 5 by Conlon; chapter 6 by Singleton). This is true for all readers, but sensitivity varies. Larger text size, rounder fonts, and more space between words and lines all lead to measurably faster reading rates and better reading comprehension (chapter 4 by Wilkins, p. 68-69). For readers with dyslexia, these factors can become significant stumbling blocks. Changing text- background contrast electronically or with colored overlays, choosing the right font (Verdana, not Times New Roman), enlarging text, and text spacing are all tools to investigate with struggling readers (or for anyone who finds reading tiring). Lighting also affects reading. Flickering fluorescent bulbs should be replaced and in many cases, lighting levels should be reduced (chapter 4 by Wilkins, p. 69).
Several authors discuss the brain pathways involved in the visual aspects of reading. There are neurons of different sizes carrying information from our eyes (retina) to the occipital lobe (vision) and to areas involved in interpreting visual information. One pathway is made of larger cells (the magnocellular pathway (M)). This pathway carries information about motion (which includes the motion involved in scanning text) and carries coarser-grain information. The M pathway interacts with the cerebellum for coordinated eye movement. Information travels along this pathway slightly faster than it does in smaller cells (the parvocellular pathway (P)). The M and P pathways work together to identify the world around us—or the words in a line of text—the M pathway telling us “where,” and roughly, “what” and the P pathway giving us more specific “what” information once location is fixed. Almost every author in this book presents evidence for M pathway deficits in dyslexia. Faulty eye movement and fixation deficits lead to experiences of visual distortion including blurring, doubling, and reversals. When two eyes can’t fixate on a word well, or in a coordinated way, the rest of the system can’t follow through to read it.
M pathways are probably also involved in perception of auditory information and may be involved with auditory processing disorders. Both visual and auditory M pathways may affect deficits in phonological processing.
My client began vision therapy with a developmental optometrist after a diagnosis of astigmatism and amblyopia in both eyes. Nine months later he had completed office visits for vision therapy and continued only with eye exercises at home. He can see one line of text instead of two. He is beginning to read with fluency, to write with more control and fewer reversals, and he is developing more self-confidence. Addressing the vision issues didn’t eliminate his dyslexia, but vision therapy certainly made it possible for remediation to progress. My new appreciation of these issues has helped me identify other struggling/ below-level readers who may need assessment of binocular vision problems. Several lines of research are developing ways to identify these problems even in preschool children (chapter 8 by Facoetti). Educational therapists must consider binocular vision screening (binocular convergence and visual tracking ability) in addition to visual acuity as part of a thorough assessment.
American Academy of Pediatrics, Section on Ophthalmology, Council on Children with Disabilities, American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and American Association of Certified Orthoptists. (2009). Joint statement—learning disabilities, dyslexia, and vision; Pediatrics 124 (pp. 837- 844). (Free full text available on-line at http://www.ncbi.nlm. nih.gov/pubmed/19651597)
Dehaene, S. (2009). Reading in the brain: the science and evolution of a human invention. New York, NY: Viking, Penguin Group.
Warner, J. (2010, March 14). Concocting a cure for kids with issues. The New York Times (New York, NY).
Nancy Knop has worked as a research scientist and as a science teacher in the biological sciences. She became an educational therapist in 2003 and worked in school, at the Appalachian Reading Center in Charleston, West Virginia, and currently through Summit Center in Walnut Creek, California. Her training as a scientist keeps her asking questions and seeking answers about the brain and learning by reading and reviewing peer-reviewed research in neuroscience and cognitive science.