Concussion in Kids: Less-Recognized Visual Changes

Here, Christina Master, MD, a pediatric sports medicine specialist at the Children’s Hospital of Philadelphia (CHOP) talks about vision issues following concussion in children.

«In our clinical and research practice here at CHOP, we have found that a number of children have visual issues after a concussion, but they’re not typically visual acuity issues. This is something we’d like to get the message out about.

The kids we see in our offices who have had a concussion often also have oculomotor issues (eye movements), whether they are related to problems with smooth pursuits (following an object), saccadic function (going from one object to another), or the vestibulo-ocular reflex function (vision and balance).

We find that they are often very sensitive to motion and vestibular stimuli, especially from busy and active environments. We also find that they have issues in school in regard to looking back and forth between a notebook, smartboard, monitor, or tablet. We’d like you to keep an eye out for these oculomotor issues. Many of them also seem to be related to binocular visual function (how the eyes function together); in particular, we notice that a convergence insufficiency can be a problem. These kids have problems focusing on objects that are far, and then transitioning from far to near and near to far again.

Photo from: https://www.todaysparent.com/kids/kids-health/concussions-hockey-problem/

As you can imagine, much of schoolwork is very visually oriented, and these issues can present problems. What we would encourage everyone to remember when assessing a child who has had a concussion is not only to look at visual acuity but also to assess oculomotor function, including smooth pursuits, saccades, and convergence. In treating these kids as they gradually return to school, it is also often helpful to recommend accommodations to allow them to have extra time, printed notes, larger-font printed materials, and, in general, extra support from a visual standpoint while their functions recover over time.

Please remember these issues when you’re evaluating kids in your office with concussion. Remember that these issues are not just about visual acuity but also include oculomotor and binocular visual issues like convergence insufficiency.»

From: http://www.medscape.com/viewarticle/876689

 

Eye Test Screens for Traumatic Brain Injury, Concussion

 

 

Photo from: https://www.washingtonparent.com/articles/1503/1503-concussions-in-kids-dr-bills-advice-for-worried-parents.php

Of the more than 340,000 cases of traumatic brain injury clinically confirmed from 2000 to 2015, mild injury accounted for 82.5%, according to US Department of Defense statistics.

However, traumatic brain injury is often only identified when moderate or severe head injuries have occurred, leaving mild cases undiagnosed, Dr Capó-Aponte and his colleagues explain in their scientific poster.

“Since approximately 30 areas of the brain and seven of the 12 cranial nerves deal with vision, it is not unexpected that the patient with traumatic brain injury may manifest a host of visual problems, such as pupillary deficit, visual processing delays, and impaired oculomotor tracking and related oculomotor-based reading dysfunctions,” Dr Capó-Aponte pointed out.
To see whether they could identify reliable biomarkers of mild traumatic brain injury that could be detected with an easily reproducible screening test, he and his colleagues looked for subtle visual changes that could be measured in the office or in the field.

From: http://www.medscape.com/viewarticle/865691

Vision and the Brain

The visual system includes 25 neocortical areas that are predominantly or exclusively visual in function, plus an additional 7 areas that are regarded as visual-association areas on the basis of their extensive visual inputs. A total of 305 connections among these 32 visual and visual-association areas have been reported. This represents 31% of the possible number of pathways if each area were connected with all others. The actual degree of connectivity is likely to be closer to 40%. The great majority of pathways involve reciprocal connections (in both directions) between areas.

From : https://www.ncbi.nlm.nih.gov/pubmed/1822724

 

Since approximately 60% of the nerve pathways are related to the processing of visual information, it is not surprising that severe visual problems occur in one or more concussions.

 

10 things you need to know about concussions

1. A concussion is a brain injury that can cause a variety of easy-to-miss symptoms. Doctors can’t “see” concussions using imaging. You don’t need to lose consciousness and a well-fitting helmet will not necessarily prevent one.

2. Symptoms can include headache, nausea, vomiting, light sensitivity, dizziness, confusion, slurred speech, poor balance, irritability, memory problems, blurred vision, sleepiness, sadness, anxiety or feeling in a fog. If you suspect a concussion, call the doctor.

3. If his head hurts, he’s off the ice, no questions asked. It doesn’t matter if he’s in the third period of a tied championship game.

4. Do not give Advil or Aspirin. Administered in large amounts, Advil and Aspirin can cause further bruising or internal bleeding. Tylenol is a safer bet; ask your doctor about proper dosages.

5. For the first 48 hours, be vigilant for signs of deterioration. Severe headache or persistent vomiting means you should go to the ER.

6. Concussion risk increases with each one. The brain is more likely to get reinjured if it hasn’t properly healed the first time. A child’s brain needs both physical and mental rest to heal (no jumping, no math problems).

7. Screens exacerbate a concussion headache. That means you have to limit the three things kids are most addicted to: TV, computer and phone.

8. If he says his head hurts, and the pain won’t go away, believe him—even if, ordinarily, your kid will do anything to skip school. The boredom of staying home and off screens will drive him—and you—so batty, there’s no way he’s faking.

9. His brain needs to rest in a dim room. This means no screens, pulling the curtains and keeping sunglasses handy. Contact teachers about making up homework in stages and catching up gradually.

10. Don’t send him back to school or sports until he’s symptom-free. Even with a mild concussion, this means no school or sports for at least a week—sometimes two.

From: https://www.todaysparent.com/kids/kids-health/concussions-hockey-problem/

Does handwriting matter?

Not very much, according to many educators. The Common Core standards, which have been adopted in most states, call for teaching legible writing, but only in kindergarten and first grade. After that, the emphasis quickly shifts to proficiency on the keyboard.

But neuroscientists say it is far too soon to declare handwriting a relic of the past. New evidence suggests that the links between handwriting and broader educational development run deep.

Children not only learn to read more quickly when they first learn to write by hand, but they also remain better able to generate ideas and retain information. In other words, it’s not just what we write that matters — but how.

“When we write, a unique neural circuit is automatically activated,” said Stanislas Dehaene, from the Collège de France in Paris. “There is a core recognition of the gesture in the written word, a sort of recognition by mental simulation in your brain.

“And it seems that this circuit is contributing in unique ways we didn’t realize,” he continued. “Learning is made easier.”

A 2012 study led by Karin James, from Indiana University, lent support to that view. Children who had not yet learned to read and write were presented with a letter or a shape on an index card and asked to reproduce it in one of three ways: trace the image on a page with a dotted outline, draw it on a blank white sheet, or type it on a computer. They were then placed in a brain scanner and shown the image again.

The researchers found that the initial duplication process mattered a great deal. When children had drawn a letter freehand, they exhibited increased activity in three areas of the brain that are activated in adults when they read and write: the left fusiform gyrus, the inferior frontal gyrus and the posterior parietal cortex.

By contrast, children who typed or traced the letter or shape showed no such effect. The activation was significantly weaker.

Dr. James attributes the differences to the messiness inherent in free-form handwriting: not only must we first plan and execute the action in a way that is not required when we have a traceable outline, but we are also likely to produce a result that is highly variable.

In another study, Dr. James is comparing children who physically form letters with those who only watch others doing it. Her observations suggest that it is only the actual effort that engages the brain’s motor pathways and delivers the learning benefits of handwriting.

The effect goes well beyond letter recognition. In a study that followed children in grades two through five, Virginia Berninger, a psychologist at the University of Washington, demonstrated that printing, cursive writing, and typing on a keyboard are all associated with distinct and separate brain patterns — and each results in a distinct end product. When the children composed text by hand, they not only consistently produced more words more quickly than they did on a keyboard, but expressed more ideas. And brain imaging in the oldest subjects suggested that the connection between writing and idea generation went even further. When these children were asked to come up with ideas for a composition, the ones with better handwriting exhibited greater neural activation in areas associated with working memory — and increased overall activation in the reading and writing networks.

Samples of handwriting by young children. Dr. James found that when children drew a letter freehand, they exhibited increased activity in three significant areas of the brain, which didn’t happen when they traced or typed the letter. Credit Karin James

It now appears that there may even be a difference between printing and cursive writing — a distinction of particular importance as the teaching of cursive disappears in curriculum after curriculum. In dysgraphia, a condition where the ability to write is impaired, usually after brain injury, the deficit can take on a curious form: In some people, cursive writing remains relatively unimpaired, while in others, printing does.

Dr. Berninger goes so far as to suggest that cursive writing may train self-control ability in a way that other modes of writing do not, and some researchers argue that it may even be a path to treating dyslexia. A 2012 review suggests that cursive may be particularly effective for individuals with developmental dysgraphia — motor-control difficulties in forming letters — and that it may aid in preventing the reversal and inversion of letters.

Two psychologists, Pam A. Mueller of Princeton and Daniel M. Oppenheimer of the University of California, Los Angeles, have reported that in both laboratory settings and real-world classrooms, students learn better when they take notes by hand than when they type on a keyboard. Contrary to earlier studies attributing the difference to the distracting effects of computers, the new research suggests that writing by hand allows the student to process a lecture’s contents and reframe it — a process of reflection and manipulation that can lead to better understanding and memory encoding.

Reflection: Instead of giving a computer for continuous use to children with academic difficulties, such as dysgraphia, the child may have to be trained to write as well as he can (while using his computer) instead of giving up! Motor training can only help the child to write better. But as today, things that do not require any effort seem to take precedence. So, it is up to you, parents, to lead this battle!

From:
Karin H. James KH, Engelhardt L. The effects of handwriting experience on functional brain development in pre-literate children. Trends in Neuroscience and Education. Volume 1, Issue 1, December 2012, Pages 32–42

British study examines mobile phone effects on children

British scientists launched a major government-commissioned study on Tuesday into the effects of mobile phone usage on the developing brains of children.

About 2,500 children from London will be tested at the age of 11 and 12 and then again two years later, to assess how their cognitive abilities develop in relation to their changing use of phones and other wireless technologies.

 Source : http://cypressinternalmedicine.com/wp-content/uploads/2011/11/photo-1.jpg

Professor Patrick Haggard, deputy director of the Institute of Cognitive Neuroscience at University College London, said it was the “largest follow-up study of its kind in adolescents worldwide”.

The World Health Organisation says there is no convincing evidence that mobile phones affect health, but existing data only goes back about 15 years.

In the study, the children will undertake classroom-based computerised tasks to measure cognitive abilities such as memory and attention.

“Cognition is essentially how we think, how we make decisions and how we process and recall information,” said Dr Mireille Toledano of Imperial College London, the principal investigator on the study.

Participants and their parents will also be asked questions about how they use mobile phones and other devices, and other aspects of their lifestyle.

An estimated 70 percent of all 11- to 12-year-olds in Britain now own a mobile phone, rising to 90 percent by the age of 14, according to the researchers.

The Study of Cognition, Adolescents and Mobile Phones (SCAMP) is being carried out by Imperial College London at the commission of the British Department of Health.

Letters were sent out to 160 different schools inviting them to enrol pupils, and tests will begin at the start of the new school year in September.

Imperial College is already involved in a separate international study, called Cosmos, into the possible long-term health effects of mobile phones on 290,000 adults in five European countries.

Video Displays and Dry Eye in Children

Source: http://www.practiceupdate.com/journalscan/9378

In a population of Korean children in grades 5 and 6 (ages 9–11), the authors compared symptoms and use of video display terminals in those with dry eye disease (9.7%, as determined by ophthalmic exam) with children without clinically determined dry eye. The risk factors for dry eyes in this population were related more to smartphone use (including mean duration of use, as reported by questionnaire) than to either computer or television viewing.

Photograph from Thomas PLESSIS (T.P Photographie)

                               With permission

                     http://www.thomas-plessis.com

 

The authors remind to keep the possibility of dry eye, which seems to be related to increased smartphone use, in mind in this population.

It is not uncommon for children between the ages of 9 and 11 — the population studied here — to exhibit potential signs of dry eye, which might include frequent blinking. Parents of children in this age range might also notice frequent or deep blinking behaviors that can be associated with tics or spasmodic blinking due to stress or anxiety.

The authors provide evidence that some of the signs and symptoms of ocular or visual discomfort can be associated with dry eyes. However, the jury is out on correlation or causation because the rate of dry eye signs was significantly greater in children with more smartphone use. The authors note that other visual factors have been reported as potentially associated with sustained smartphone use, such as accommodative issues and transient myopia. Because dry eye disease is not widely recognized as a potential problem in this age range, it adds to considerations in differential diagnosis of visual and ocular problems in childhood.

Two-hundred eighty-eight children were classified in either a dry eye disease group or control group according to the diagnostic criteria of dry eye disease. The results of ocular examinations, including best-corrected visual acuity, slit-lamp examination, and tear break-up time, were compared between groups. The results of questionnaires concerning video display terminal use and ocular symptoms were also compared.

Twenty-eight children were included in the dry eye disease group and 260 children were included in the control group. Gender and best-corrected visual acuity were not significantly different between the two groups. Smartphone use was more common in the dry eye disease group (71%) than the control group (50%) (P = .036). The daily duration of smartphone use and total daily duration of video display terminal use were associated with increased risk of dry eye disease (P = .027 and .001, respectively), but the daily duration of computer and television use did not increase the risk of dry eye disease (P = .677 and .052, respectively).

The results showed that smartphone use is an important dry eye disease risk factor in children. Close observation and caution regarding video display terminal use, especially smartphones, are needed for children.

Study source: JH Moon, MY  Lee, NJ Moon. Association Between Video Display Terminal Use and Dry Eye Disease in School Children. J Pediatr Ophthalmol Strabismus 2014 Mar 01;51(2)87-92.

Researchers recommend increasing time spent outdoors during school

Decidedly, studies on myopia and vitamin D or activities spent outside keep coming!

Results of a study involving 2,000 first-grade students prompted the researchers to suggest mandatory targets for the amount of time children spend outside during school hours.

Ian G. Morgan, PhD, of the Research School of Biology, Australian National University, Canberra, and the Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China, reported results of the Guangzhou Outdoor Activity Longitudinal Study here at the Association for Research in Vision and Ophthalmology meeting.

“The prevalence of myopia in East Asia has increased dramatically in the last 50 years, and a slower increase has been seen in Europe and North America,” Morgan said in his presentation.

The prevalence of high myopia, considered to be at least -6 D, is 20% in East Asia, he said, and prevention becomes essential.

The researchers recruited more than 2,000 first-grade students in 12 primary schools in Guangzhou. The school had been involved in previous studies, so records on visual acuity assessment dating back 20 years were available for children from this school, Morgan said.

One 45-minute class of outdoor activity was added at the end of the day, and children in the control group went home at the normal time, he said. The two groups of children were matched for prevalence of myopia, mean spherical equivalent and axial length.

Over the 3-year period, cumulative incident myopia was 39.5% in the control group and 30.4% in the intervention arm, a reduction of 23%, according to the study abstract.

“Differences in axial length did not quite reach statistical significance,” Morgan said. “It seemed to indicate that by increasing the amount of time outdoors, we were able to lower the level of incident myopia and prevalence of myopia. This is apparently a dose-response relationship.”

“We, therefore, recommend that myopia control programs based on increased time outdoors be developed in primary schools, at least in countries with currently high prevalence rates for myopia, with evidence-based mandatory targets for the amount of time children spend outdoors,” the authors concluded in their abstract.

 ?

Morgan asked: “Is the mechanism brighter light and increased dopamine release outdoors, or is it increased UV exposure outdoors? Evidence from animal studies favor the light-dopamine hypothesis, but a clinical trial of vitamin D needs to be done.”

From:

http://www.healio.com/optometry/optics/news/online/%7B5f21032e-c14c-4e33-96c2-345d7beaa63a%7D/researchers-recommend-increasing-time-spent-outdoors-during-school

New study finds vitamin D may be related to myopia in adolescents

Recently, researchers in South Korea have found that vitamin D levels may relate to severity of myopia.

Previous research has found that spending more time outdoors may help protect against developing myopia. This has led some researchers to speculate that vitamin D may play a role in myopia, as outdoor sun exposure is the main way for humans to produce vitamin D.

In the present study, researchers at the Catholic University of Korea in Seoul, South Korea looked at data from a national sample to determine if vitamin D relates to myopia. They used data from the Korea National Health and Nutrition Examination Survey (KNHANES). KNHANES is an ongoing population-wide survey that collects data on health and nutritional status of people in South Korea.

The researchers looked at data from 2,038 people aged 13 to 18 years old who had participated in KNHANES. The researchers examined their vitamin D levels, and noted whether they had myopia, and how severe their myopia was.

They wanted to know if vitamin D levels were related to the prevalence and severity of the condition. Of the 2,038 participants, 80.1% had myopia and 8.9% had very severe myopia. The researchers found that vitamin D levels were related to severity of myopia. This means lower vitamin D levels were related to more severe myopia among the participants.

“We found a significant association between low serum [vitamin D] concentration and myopia in Korean adolescents aged 13 to 18 years,” the researchers stated.

The researchers called for efforts to raise vitamin D levels among children through supplementation and outdoor activity in order to prevent the development of myopia.

To be followed…

Source:  http://www.vitamindcouncil.org/

Myopia: a world tour

The eye’s shape depends on growth that occurs primarily during infancy, and to a lesser extent through adolescence. We think that growth is ruled in part by genetic instructions that humans have evolved over many millennia; if the genetic blueprint is defective, eyesight can certainly suffer. But growth of the eye also depends heavily on external cues — what scientists call visual feedback. The bombardment of light, with its colors and contrasts, and use of the eyes (reading, computer work, etc.) help guide proper or improper eye growth.

Scientists are now convinced that something about the visual environment and the use of the eys in this environment has changed drastically in recent decades, and those changes are driving the onslaught of nearsightedness seen in teens and young adults. From the early 1970s to the turn of the century, myopia prevalence in the United States rose from 25 percent to nearly 42 percent among people ages 12 to 54, a substantial shift in just one generation. The rate among U.S. young adults is 38 percent, up from 28 percent in the 1970s. On the other side of the globe, myopia rates in Singapore, which has gone from a sleepy port city to a center for international commerce, have risen from 43 percent among military conscripts (all young men) in the late 1980s to more than 80 percent today.

Meanwhile, older generations haven’t experienced a sharp rise in the disorder. The rate in people over age 40 inChina and the United States is at about one-fourth.

Rural vs urban life

Studies suggest that rates of nearsightedness differ in ethnically related populations living in rural versus urban areas (data from country to country may not be comparable). City living appears to have a detrimental effect on visual problems (I. Morgan and K. Rose/Progress in Retinal and Eye Research 2005).

Because such increases also have not shown up in rural areas, scientists think the trend reflects new behaviors among young urbanites. With more people moving to cities, the trend is likely to worsen. For some, nearsightedness will be a mere inconvenience. But others, who develop high-degree myopia, will have worsening vision over time and a greater risk of cataracts, glaucoma or a detached retina later in life. Of those young men in Seoul and students in Shanghai who are nearsighted, roughly one in five already has high-degree myopia.

This graph shows the prevalence of myopia in China, Vietnam, India and Nepal whether people live in a rural or urban area. We see that the people who live in rural areas (with a school system probably more demanding) have a higher prevalence.

“There will be an epidemic of pathological myopia and associated blindness in the next few decades in Asia,” says Seang-Mei Saw, a physician and epidemiologist at the National University of Singapore.

The new wave isn’t genetic, Morgan says. “The gene pool can’t change that much in a generation, not even in several,” he says.

The other behavioral change that may not mesh well is near work. Human forebears didn’t read, and even those who chipped arrow points or did other fine work probably didn’t do it all day, every day. Frequent near work arrived with civilization; in many societies, it came about in the last century or two. A lot of myopia develops during childhood, and there may be some science behind the stereotypical bookworm with thick glasses. Myopia can also show up in adulthood, depending on the quantity of near work done. This is called occupational myopia.

Recent work by several researchers argues that “reading, writing and computer work will contribute to myopia, and that children who regularly spend much time on computers have a higher risk of myopia.”

 A world tour…

Source: Epidemiology (http://en.wikipedia.org/wiki/Myopia)

The global prevalence of refractive errors has been estimated from 800 million to 2.3 billion. The incidence of myopia within sampled population often varies with age, country, sex, race, ethnicity, occupation, environment, and other factors. Variability in testing and data collection methods makes comparisons of prevalence and progression difficult.

The prevalence of myopia has been reported as high as 70–90% in some Asian countries, 30–40% in Europe and the United States, and 10–20% in Africa. Myopia is less common in African people. In Americans between the ages of 12 and 54, myopia has been found to affect African Americans less than Caucasians.

Asia

In some parts of Asia, myopia is very common. Singapore is believed to have the highest prevalence of myopia in the world; up to 80% of people there have myopia, but the accurate figure is unknown. China’s myopia rate is 31%: 400 million of its 1.3 billion people are myopic. The prevalence of myopia in high school in China is 77.3%, and in college is more than 80%. However, some research suggests the prevalence of myopia in India in the general population is only 6.9%.

Europe

A recent study involving first-year undergraduate students in the United Kingdom found 50% of British whites and 53.4% of British Asians were myopic.

United States

Myopia is common in the United States, with research suggesting this condition has increased dramatically in recent decades. In 1971-1972, the National Health and Nutrition Examination Survey provided the earliest nationally representative estimates for myopia prevalence in the U.S., and found the prevalence in persons aged 12–54 was 25.0%. Using the same method, in 1999-2004, myopia prevalence was estimated to have climbed to 41.6%.

Australia

In Australia, the overall prevalence of myopia (worse than −0.50 diopters) has been estimated to be 17%. In one recent study, less than one in 10 (8.4%) Australian children between the ages of four and 12 were found to have myopia greater than −0.50 diopters. A recent review found 16.4% of Australians aged 40 or over have at least −1.00 diopters of myopia and 2.5% have at least −5.00 diopters.

Epidemic myopia in Asia

Source: http://blogs.discovermagazine.com/80beats/2012/05/12/why-are-90-of-asian-schoolchildren-nearsighted-from-doing-what-youre-doing-now/#.UTNmJ5aEXjY (Why Are 90% of Asian Schoolchildren Nearsighted? From Doing What You’re Doing Now –  By Sarah Zhang)

The sheer prevalence of nearsightedness, or myopia, among Asian schoolchildren (in Singapore, China, Taiwan, Hong Kong, Japan, and Korea) is stunning: 80 to 90% according to a recent review in the journal Lancet. In comparison, that number is just 20 to 30% in the UK. Myopia has also been on the rise in both Asia and Europe over the past few years.

In Singapore, myopia has shot up in the last 30 years among all three major ethnic groups—Chinese, Indian, and Malay—which highly suggests a environmental cause. Singaporean schoolchildren who read more than two books per week were also more likely to have myopia. How one reads physically, may have an impact too: ultra-orthodox Jewish boys, who study the Torah intensely and at a close distance while swaying, have higher myopia numbers than the girls, who don’t. Together, these observational studies suggest that high myopia rates in Asian schoolchildren are likely related to their intense educational systems.

Change in prevalence of myopia among three ethnic groups in Singapore. The following numbers Figures are approximate and are taken from the illustration above.

                                       China             India              Malaysia

1987-1992                     48%                29%                  25%

1996-1997                     80 %              70%                  65%

2009-2010                     85%               75%                  70%

Also adapted from : http://www.sciencenews.org/view/feature/id/347738/description/Urban_Eyes – By Nathan Seppa

 

Myopia and outdoor activities: new study

For about 5 years, a new theory was launched: kids who do not play outdoors regularly are on average more myopic (or less farsighted) than those who practice outdoor activity on a regular and prolonged basis. Children with few outdoor activities and who practice activities requiring near vision (reading, video games on portable console, etc.) were three times more likely to be myopic as those who practice many outdoor activities and some reading activity.

Professor Ian Morgan (from the Australian National University), highlights another risk factor: for him the crucial factor is simply the lack of natural light. A neurotransmitter produced in the retina under the influence of light, dopamine, could avoid excessive growth of the eye in childhood. If spending hours reading, playing or working on a screen promotes myopia, according to Morgan, this is indirectly because children spend much less time outside {1}.

These data were corroborated with those of a study of adolescents in Singapore, which were much less myopic (or farsightedness) when they practiced much more outdoor activities. {2}

It seems that this is the time that is spent outside that protects against myopia, rather than the sport itself (no influence of indoor sports on the prevalence of myopia). This was corroborated by a more recent study by Guggenheim et al. {3}

1. Rose et al. Outdoor activity reduces the prevalence of myopia in children. Ophhalmology 2008 115: 1279–1285.
2. Dirani et al. Outdoor activity andmyopia in Singapore teenage children. Br J Ophthalmol. 2009; 93: 997–1000.
3. Guggenheim JA, Northstone K, McMahon G, Ness AR, Deere K, Mattocks C, St Pourcain B, Williams C. Time outdoors and physical activity as predictors of incident myopia in childhood: A prospective cohort study Invest Ophthalmol Vis Sci. 2012 Apr 6.

Source: http://www.alancarlsonmd.com/wp-content/uploads/2011/06/im084057.jpg

New study

Another recent study (February 2013) conducted in Denmark shows that for children with myopia, vision deteriorated rapidly when the days were shorter (winter period) and more slowly during the summer months. This study aimed to determine whether daylight could slow the progression of myopia in children.

“Most likely it is the light exposure that causes the reduced myopia progression during periods with longer days,” said lead author Dr. Dongmei Cui, an ophthalmologist at SunYat-senUniversity in Guangzhou, China.

Cui and his colleagues analyzed data from a clinical trial that included more than 200 children aged 8 to 14 years old with myopia, or nearsightedness, in Denmark – where day length ranges from seven hours in winter to almost 18 hours in summer.

Over the six months with the least daylight, nearsightedness progressed by 0.32 diopter. In comparison, children’s vision deteriorated by 0.28 diopter over the sunniest months.

Accumulated hours of daylight ranged from 1660 to 2804 hours. Significant correlations were found between hours of daylight and myopia progression (P = 0.01). In children with an average of 2782 ±19 myopic progression was greater.

With the increase in the length of the eyeball (axial length) from the front to the back, myopia tends to worsen. During the winter period, the axial length among study participants increased by an average of 0.18 mm compared to 0.14 mm in the summer, according to results published in the journal Ophthalmology.

Note: if statistically there is a difference in the progression of myopia between the two groups, can we say that these results are clinically significant? No! Over a period of one year, we can estimate an increase of 0.60 diopter if the children of both groups react in the same way. The only difference is the seasonal variation during the year.

Source: http://www.cataract.com.sg/neuro.htm

The researchers did not analyze how much time the children spent outside, just how much they probably did based on the season. Danish children spend much more time outdoors in summer, and very little in winter, when temperatures hover around freezing for four months, according to Cui.

Past research on nearsightedness in children in the U.S. found the condition deteriorated more during the six months of the school year and less during the six months that include summer. But another study in Singapore, where days are about the same length all year, found no seasonal difference in the progression of nearsightedness.

The idea that daylight might protect children from worsening nearsightedness is a relatively new theory, said professor Jeffrey Cooper of the College of Optometry at the State University of New York in Manhattan.

Studies in mammals and birds have found that light exposure plays a role in the development of the eye, and that animals reared from a young age with frequent exposure to high intensity light may be somewhat protected from myopia. No similar effect has been seen with light exposure in adulthood.

The new study’s results can’t prove that daylight causes vision loss to slow down, Cooper said. “There is no evidence that increasing outside exposure will actually reduce the progression of myopia,” Cooper, who was not involved in the work.

Reading processes and visual or surface «dyslexia» – part 2

Lexical or whole-word reading

Competent reading essentially involves the whole-word or lexical process of reading which ensures fluent reading and a “direct” access to meaning. It recognizes the shape of the word and immediately find its sound correspondence in memory (or phonological), the meaning of the word being evoked, which is the ultimate goal of reading.

The whole-word process (or eidetic = photographic), both more automatic and faster, can even bypass the phonological pathway, which is more controlled and slower. Most of the time, the expert reader would not need to use his phonological knowledge to recognize written words. The observation of a double dissociation between visual and phonological dyslexia in patients with brain damage is an argument in favor of the neuropsychological existence of the two independent procedures for the recognition of written words (Coltheart, Masterson, Byng, Prior & Riddoch, 1983; Funnell, 1983; Shelton & Weinrich, 1997). Numerous studies supporting these models have also emphasized the optional phonological code while reading (Peereman, 1991, for a review).

Coltheart M, Masterson J, Byng S, Prior M, Riddoch J. Surface dyslexia. Q J Exp Psychol A. 1983 Aug;35(Pt 3):469-95.

Funnell E. Phonological processes in reading: new evidence from acquired dyslexia. Br J Psychol. 1983 May;74 (Pt 2):159-80.                     

Weinrich M, Shelton JR, McCall D, Cox DM. Generalization from single sentence to multisentence production in severely aphasic patients. Brain Lang. 1997 Jun 15;58(2):327-52.

Peereman R. Phonological assembly in reading: lexical contribution leads to violation of graphophonological rules. Mem Cognit. 1991 Nov;19(6):568-78.

When the child becomes able to recognize a word as a unit, he gradually builds his orthographic lexicon. The operation of this lexicon is not yet fully known, but it seems to be like a dictionary which exists in our brain, allowing rapid identification (the faster the more familiar word) and immediate access to meaning.

This procedure then develops to become more and efficient as reading becomes more competent. Ultimately, the adult reader would only use the “photographic” procedure, which is obviously much faster than going through words syllable by syllable (which remains necessary when we must read for example, new or meaningless words or of a foreign language).

http://www.coridys.asso.fr/pages/base_doc/txt_habib/entree.html

Imagine a child who reads the following sentence:

“The locomotive arrives at the station”

versus

“The-lo-co-mo-ti-ve-ar-ri-ves-at-the-sta-tion“.

(or syllable by syllable)

 

In the first case, the child immediately recognizes the words and understands what he reads. In the second case, the child does not read words but syllables one by one. Difficult to quickly understand what is read.

Surface dyslexia

Surface dyslexia, in its pure form, is characterized by a selective impairment of reading irregular words while reading regular words and pseudo-words is relatively preserved. This selective difficulty reading irregular words translates a dysfunctionnal lexical reading procedure.

These children do not present associated disorders of oral language and have good capabilities in short term verbal and workong memory and have good phonological awareness. They also have difficulties in visual processing that make comparing sequences of letters or identify targets among others.

It is said that pure forms of surface dyslexia are relatively rare in clinical practice. But I can assure you that in my optometric practice, these children are much more numerous than the statistics show.

Visuo-attentional dyslexia

There is also, according to some authors, another form of dyslexia, called “visual-attentional” where the child has a good memory of the spelling of words and is able to transcribe sounds into words. For cons, the type of errors encountered in this disorder is reversals in groups of letters, omissions, additions, approximate reformulations, skippng lines while they read.  line breaks. The child may confuse letters and words with others closely resembling it. It would be a disorder affecting necessary attention for an effcient reading activity.

(In : http://www.ac-grenoble.fr/ia73/spip/IMG/pdf/dys_apedys.pdf)

These children also have oculomotor (eye movement) and visual discrimination problems, difficulties in visual attention, difficulties in copying material from a book or the blackboard.

It is difficult to conceive a child who has a serious visuo-attentional problem would not show a form of surface dyslexia. There is certainly a very close relationship between the two since both can prevent the establishment of a proper orthographic lexicon. They may also be different manifestations of the same problem called “visual dyslexia”. This close relationship between visual and attentional problems is reinforced by the significant progress in reading and spelling seen in a child with surface dyslexia following a trainign program focused on visual processing capabilities (Launay and Valdois , 1999)

Valdois S, Launay L. Évaluation et rééducation cognitives des dyslexies développementales: illustration à partir d’une étude de cas.  In : La rééducation neuropsychologie : Études de cas. AZOUVI P, PERRIER D, VAN DER LINDEN M (eds). Marseille, Solcoll, 1999 : 95-116).

 Visual-perceptual skills essential to insure adequate whole-word reading

It is probably unnecessary to say that the best readers are those who read in a whole-word fashion, this  method of reading is fast and understanding is also much better. But what is the action to take if a child uses no or has a poor orthographic lexicon? We must ensure that the related visual and perceptual skills are adequate. Otherwise, visual training will be needed to improve these skills.

What are the skills that have a close relationship with the development of orthographic lexicon? First, eye movements: reading requires a constant movement of the eyes along a line of text, which is done by a series of short jumps (saccades) interspersed with longer breaks during which takes place all intake of visual information. These jumps between fixations are very short, about one-thirtieth of a second. Saccades take approximately 250 to 300ms. Saccades are also an index of visual attention. We have tests that evaluate the speed, accuracy and fluency of reading. Eye movement problems hamper efficient learning and reading quality (failure to follow the text, loss of place, jump words or lines, etc.). For reading to be effective, eye movements must be flexible, fast and accurate.

Then visual attention and concentration allow the child to remain focused and attentive to every detail of what we see and as long as necessary. Attention and concentration are a preqequisite to good visual discrimination. In addition, visual attention is the link between perception (making information available) and cognition (use this information). It ensures maximum reception all the information from our visual environment. Visual concentration promotes maximum use of working memory to collect, store, retrieve and process the relevant information. It facilitates the work and especially the intellectual performance.

Short-term and sequential visual memories allow the child to recognize an item after a brief exposure, or to recall items in the same order and in the same sequence. For example, remembering the order of letters in a word or words in a sentence with a quicker understanding of what is read. Children who show difficulties in visual sequential memory may have difficulties copying information from the board or a book, to learn to read mulriple words or sentences and remember what they read. They may also have difficulties in creating their orthographic lexicon, which affects fluency and reading comprehension.

Visualization or mental imagery is the ability to create images of a word, a sentence or a paragraph in our head (our mental picture). This ensures good understanding of what is read and allows a better organization of information, making it easier to retain and build an efficient orthographic lexicon. This perceptual skill is also essential for mental arithmetic and spelling of words. If a child reads a story without being able to mentally see the scene described in the text, then this will influence contextual

In summary, the eyes must move effectively to ensure high quality of visual information, and the child must be able to remain attentive and focused on what he reads. Visual memory will also allow to recognize the same words in a text. Many children can not build a orthographic lexicon because they can not even recognize a word they just read and read again a few lines later. Visualization allows the child to “juggle with words” in his head. And finally, it is practicing reading every day that ensures efficiency in reading. More often we see the same words, the faster they will be included in the orthographic lexicon.

Conclusion

According to scientific research, three basic skills (among others) will thus directly influence reading performance in children: visual memory, visual attention and visualization. The best readers are capable of recognizing whole words easily (eidetic, global or whole-word reading). This accelerates visual decoding, requires less energy and promotes better understanding. Reading phonologically (syllable by syllable) slows down the reading process and does not guarantee an adequate understanding of a text. The best readers need not phonological awareness to read and can recognize most words without having to dissect them. That is why we have developed a particular portion of our vision therapy to enhance these perceptual abilities. We try to develop better whole-word reading to improve reading efficiency and comprehension.

Reading processes and visual or surface «dyslexia» – part 1

“True“dyslexia is seemingly a “neurological” dysfunction (of course, we read with our brain, not just the eyes!) marked by the inability of the brain centers to efficiently decode print or phonetically make the connection between written symbols and their appropriate sounds. The connotation of the word “neurological” can be confusing: this word is too easily understood or related to a nervous system disease. Dyslexia may be caused by a nervous system dysfonction, but surely not a disease!

The origin of this problem, yet ardently debated in the literature, is probably multi-causal. It is unfortunate that the researchers are constantly looking at only a small aspect of dyslexia in their studies. We also know that not all children who have difficulty reading, however, suffer from phonological processing. Although the symptoms are similar, they may also have visual and perceptual problems that interfere with adequate learning, not just a deficit-based language, as some would have us believe…

Margaret Livingstone, et al, from the Department of Neurobiology, Harvard Medical School and the Dyslexia Research Laboratory, Beth Israel Hospital in Boston reports that poor visual processing plays a significant role in a large majority of children who struggle to read:   “Several perceptual studies have suggested that dyslexic subjects process visual information more slowly than normal subjects.  Such visual abnormalities were reported to be found in more than 75% of the reading-disabled children tested.”

Livingstone MS, Rosen GD, Drislane FW, et al. Physiological and anatomical evidence for a magnocellular defect in developmental dyslexia. Proc Natl Acad Sci USA 1991; 88:7943-7.

Moreover, all children with learning difficulties in primary school are not dyslexic, and vice versa, a child may be dyslexic without it being prolonged failure (especially if dyslexia is mild and if it can be compensated by the development of other skills intact).

Essentially, there is also a problem in the clinical definition of dyslexia. Everyone has their own definition and tests used in the diagnosis of such a condition do not always lead to a clear diagnosis… This imprecision in diagnosis can also certainly explain the variability in prevalence rates reported in the literature (this rate may actually increase from 4% (Yule and Rutter, 1973) to 20% (Shaywitz, 1996)).

Yule W, Rutter M, Berger M, Thompson J. Over- and under-achievement in reading: distribution in the general population. Br J Educ Psychol. 1974 Feb;44(1):1-12. 

Shaywitz SE. Dyslexia. Sci Am. 1996 Nov;275(5):98-104.

A child in early primary school may have some difficulty learning to read, this situation is common and there is no question of going overboard and put a label of  “dyslexia” for all these children.

Decoding process of reading: the dual-route model

The dual-route model is very frequently used as a reference model for decoding during reading. This model postulates the existence of two procedures involved in both reading and writing.

Dual-route reading process

From : http://www.cognisciences.com: Outil de Dépistage des Dyslexies – Odedys2 – 2009

Phonological process

The phonological process is characterized by a sequential analytical processing or syllabic of a word or pseudo-word (invented word). It involves a system of rules for grapheme (a letter or two, sometimes three) – phoneme (sound related) explicitly learned in school.

The word “camel” when processed through this system will be segmented into graphemes <CA – MEL>, then each grapheme will be assigned to a phoneme which is most frequently associated in the language This allows to generate the sequence of the word.

Only the phonological process allows the processing of new words (words not previously learned or “pseudo-words” which are words invented for the purposes of experiment, for example: famsled, posvent or rolted).

Insofar as the treatment of new words is dedicated to this system, lists of pseudo-words are systematically tested for reading and dictation for children with difficulties, to test the integrity of the phonological process. Good performance in reading invented words indicates that the phonological process is operational, poor performance involves an inadequacy of this pathway.

It is known that the analytical (phonological) route plays a major role in early learning as it is chronologically the first. If we conceive that in adults both channels are relatively autonomous, it seems unlikely that these two pathways are also distinct in children who are learning to read.

Whole-word or eidetic process

The lexical procedure (or whole-word process) performs simultaneous processing of all the elements of the word. All units which compose the word are processed in parallel, leading to the activation of the orthographic lexicon stored in the brain and learned previously. The child sees the word and understands it immediately.

In reading, and after some visual processing, the representation of the word as a whole is activated in our orthographic lexicon (the “dictionary within our head”) and gives a very rapid access to the sound structure (phonology) corresponding to this word and its meaning. No need to decode the word syllable by syllable.

The way this lexicon functions is not yet fully known, but it seems to be like a dictionary to which we would refer for each word read, according to a “photographic” procedure, allowing rapid identification (the faster the more familiar is the word) and immediate access to meaning.

Each of the two procedures for reading (or writing) is implemented specifically for the treatment of certain types of words: the lexical route or process can only deal with words already learned and whose representations are available within the orthographic lexicon and its phonological correspondence. It is needed when reading or writing irregular words that are not pronounced the way they are written (for example, rough, soared, laugh). Irregular words that can only be handled by the lexical route is used in the evaluation of children with learning disabilities. Lists of irregular words are proposed or presented to test the integrity of the lexical route: a good performance when reading these words shows that the lexical procedure is operational; poor performance in reading irregular words compared to reading regular words or pseudo-words suggests a failure of the lexical procedure.

(Part 2 in next blog)