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Posts tagged ‘posture’

British study examines mobile phone effects on children

Photo JPL-blogueBritish 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.

blogue - fillette-iPhone

 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

Photo JPL-blogueSource: 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.

Blogue - Apple Addict

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.

Smartphones do affect vision in children

How to hold your phone so it doesn’t (completely) wreck your vision

Photo JPL-blogueSource:  http://www.marketwatch.com/story/dont-give-up-your-eyes-for-an-iphone-2013-08-23

Spending half the day staring into a 10 cm (four-inch) screen may also wreck one’s eyesight, new research suggests — and the devices may not be to blame so much as how we hold them.

David Allamby, an eye surgeon and the founder of Focus Clinics in London, recently coined the term “screen sightedness” and pointed out that according to his research, there has been a 35% increase in the number of people with advancing myopia since smartphones launched in 1997.

Allamby is concerned that use of portable devices could increase cases of myopia in children of another 50% in ten years!

Nearsightedness affects more than 30 % of the population of the U.S and more than 80% in Asia. The environmental factors that contribute include “close work,” or stress on the eye caused by reading or otherwise focusing on near visual tasks.

Using a smartphone strains the eyes in much the same way reading a book or staring at a computer monitor does, with one exception — the distance between the eye and the object. When a phone or other device is held close to one’s face, it forces the eye to work harder than usual to focus on text, says Mark Rosenfield, an optometrist. The discomfort can eventually result in fatigue.

enfant-iphone

Source: http://www.loupiote.com/photos/5391333755.shtml

People tend to hold smartphones considerably closer to their faces than they would a book or newspaper, even as close as seven or eight inches, Rosenfield says. And since smartphones have such a small screen, the importance of visual stress tends to be higher than for other devices.

Holding a smartphone farther away (but still using it the same amount) won’t necessarily prevent myopia entirely, Schaal said. But holding the phone at least 16 inches away from the face during use can be beneficial, Rosenfield says.

He also suggests taking breaks from using the phone. During those breaks, it is helpful to look into the distance, which relaxes the eye as it focuses on faraway detail instead of what is close.

Young children’s eyes may be spared early damage by limiting smartphone and tablet use, doctors say. Spending hours playing games or otherwise intently viewing a screen causes children’s eyes to exert effort for long periods. In the past, children focused on larger objects like blocks or toys, rather than such fine detail. They should be encouraged to engage in a variety of activities with different focusing targets of both near and far away objects.

Headaches, again…

In the previous text, we shared a study on headaches in children and the lack of relevance to either having to wear glasses or changing the lens power of the glasses. One of the issues discussed was the biased scientific methodology and the art of making such statements without seeing further than one’s nose…

Contrary to the statement of the authors and of the American Association of Ophthalmology, there is a source more relevant and of more scientific relevance about headaches and vision of children that is free of any bias examiner. In 2009, a major study both from optometrists and ophthalmologists concerning convergence insufficiency and its symptoms, the CITT study (Convergence Insufficiency Treatment Trial) began. They created a questionnaire called CISS (Convergence Insufficiency Symptom Survey) to link the symptoms to convergence insufficiency. All one has to do to determine if the visual requirements are linked to headaches is to ask! The CISS questionnaire showed that it could be done reliably. You will find the questionnaire at the end of the text. Note the number of items that relate to visual discomfort. You can also download it from: http://www.aoa.org/x13917.xml

Q1: Do your yes feel tired when reading or doing close work?

Q2: Do your eyes feel uncomfortable when reading or doing close work?

Q3: Do you have headaches when reading or doing close work?

Wait a second! Why is it that the best standardized questionnaire in the history of joint studies of optometry and ophthalmology, studies funded by the U.S. government, directly ask a question about headaches associated with visual tasks, while the recent study talked about “proofs beyond doubt” that it is not relevant?

Let’s dispense with the simplistic notions of the latest press release, and set the record straight:

  1. Headaches can be associated with vision problems.  Unless you ask the question, you can’t get an answer.
  2. Pediatrician screening is not a substitute for a complete eye exam performed by an optometrist. A child who complains of headache associated with visual tasks near (reading, writing, drawing, etc.) might show a functional problem (alignment problem like convergence and/or focusing), while having no problem with distance visual acuity (vision of 20/20 or 100%).
  3. A change in glasses may sometimes not completely solve the headache. But often wearing new glasses for an individual who was not wearing any will solve the problem.
  4. If the underlying cause of headaches is a functional problem, the treatment of choice according to proved scientific studies is proven optometric vision therapy.

Adapted from VisionHelp Blog (a super blog!): http://visionhelp.wordpress.com/

The abstract of the study on the CISS questionnaire can be found here: http://www.ncbi.nlm.nih.gov/pubmed/19289977

Even in ophthalmology, here is what is said about eyestrain and headaches:

“The visual symptoms are caused by because focusing of the eyes becomes increasingly difficult due to fatigue especially at the end of the day after prolonged reading. Vision becomes blurred and sometimes even double. Vision at near can be uncomfortable.

Eyestrain occurs mainly in the late afternoon as near vision is constantly at work by efforts of focusing in work and in leisure with particularly computer screens, mobile phones, television, console games…

Eye symptoms reflecting visual fatigue include a feeling of discomfort, tension, and heaviness in the region of the eye, orbit or eyelids. There may be feeling of irritation, burning, stinging, and itching, sometimes with red eyes, some tearing or irritation due to dry eye. The subject may feel dull pain but not very intense that may become acute generally behind the eyes.

Headaches can be felt around the eyes, on the forehead above the eyebrow line, temples or behind the head. These headaches are related to eye strain, occur after a certain period of work at the end of the day, fade and disappear after cessation of work.” (Source: http://www.ophtalmologie.fr/fatigue-visuelle-yeux.html)

Posture and Vision (3)

Visual Hygiene and Near Work Visual Habits

 

Some tips in brief:

  • Do all near point activity at HARMON distance or slightly further.
  • For reading, writing, and other near vision tasks it is important that the object being viewed be kept adequately far from the eyes.  The working distance should be at least 40 cm (sixteen inches) for adults and older children, and at least 30-33 cm (twelve to thirteen inches) for younger children.  When the viewing distance is shorter, the demands upon the focusing system become increased out of proportion to the few inches involved.  This increases demand can lead to severe stress and strain.
  • Therefore, maintaining an adequately long working distance is the foundation of good visual hygiene and depends upon good relaxed posture and proper lighting.  Reading and writing while lying down, reading in bed, and other inappropriate postures tend to result in shortened viewing distances.  Insufficient lighting also causes one to hold reading material inappropriately close in order to see it.
  • When reading, occasionally look off at a specific distant object and let its details come into focus. Maintain awareness of other objects and details surrounding it. Do this at least after two or three pages.
  • Desk work should be performed at an appropriately sized desk and on a surface inclined at an angle of 20 degrees. The chair should be of such size to allow the feet to rest comfortably on the floor. The buttocks should be flat and tucked fully to the back of the seat.  Kitchen or dining room tables were not designed for studying or writing.  They are usually too high and inappropriate for use by a child.  Tilt the book up about 20o.  Read in bed only when sitting upright – if at all.
  • For proper lighting when reading in a chair, illuminate the entire area using overhead/full-room lighting.  Next, have another light on your book – one that avoids bright reflection on the task.
  • When performing any prolonged near work, take breaks if you begin to feel your neck, shoulder, or back muscles beginning to tighten.
  • Don’t get “locked in” when doing close work.  Read or study no longer than fifteen to thirty minutes without interruption.  Look up at a distant object as you turn each page, and try to get the distant object clear before beginning to read the next page.  Looking back and forth from distance to near while reading reduces the tendency of the focusing muscles to become cramped.
  • Be aware of your general surroundings while reading or viewing TV.  Do not place desks against walls. Do not sit any closer to TV than is necessary.  A minimum viewing distance of 2,5 to 3 meters is reasonable.
  • Active outdoor play is an essential part of normal and healthy development.  Play activities that require seeing beyond arm’s length should be encouraged.

Inspired from:  http://www.gallopintovision.com/visual_hygiene.htm

In summary:

 The essential elements of visual hygiene tips are:

  • posture
  • distance
  • furniture
  • lighting
  • relaxation (breaks)

Posture: Sit with a straight back, with head straight, aligned for the task, neither tilted excessively forward nor backward, nor tilted to either side. This position should be maintained throughout all near activities.  Avoid reading in bed or lying down. No lying on the stomach, no slouching, no curling up or other asymmetric positions.

Distance: for reading, writing, drawing, hand-held video game, etc.: everything must be done at forearm’s length. For desktop computer, the screen should be placed at arm’s length (fingers must just barely touch the screen). For a laptop, a working distance of 50 to 60 cm is recommended.

For television: At least 2 to 3 meters, with head and back straight.

Furniture:

If children or shorter people are working on a regular table (ex kitchen table), they should sit on a higher stool or a cushion.  Otherwise, use a smaller table adjusted for their height.

Lighting:  Use general overall lighting in the room and add supplemental lighting as needed for the task.  Make sure there is even lighting across your work.  Never work in the dark.

Taking breaks: a 10 minute break after a 60 minute period is beneficial.

Note: This ends all that I had to say about myopia and the control of this condition. I hope these texts have made you more aware about myopia and that you will be able to help your child in the prevention or control of his or her myopia.

Posture and Vision (2)

Slant desk or slant board with a 20 degree angle

Ideal work surface (http://www.visualedgesb.com/)

 Many years after Harmon’s studies, Drs Pierce and Greenspan have also studied the relationship between posture and vision. Once again, they have shown that there is an integral working relationship between posture, work distance and work surface.  Their research has proven that learning performance improves when the proper conditions are established for near-point visual activities such as reading and writing.

Their studies show when work is presented on a sloped work surface, with an angle at between 20 and 23 degrees, sitting no closer than fist to elbow length from the work surface, the worker experiences a reduced heart rate, neck, muscle and overall body tension as well as a more regular and deeper breathing pattern. A slanted surface compels your body to sit in a more upright posture

  • Dr. John Pierce Rev Optometry 1977; 114:48-63
  • Dr. Steven Greenspan; Optometry Weekly 1971; 62(33): 754-757, Optometry Weekly 1971; 62(34): 776-780

Source: http://www.visualedgesb.com/

A century ago, classroom designers and teachers understood the importance of proper ergonomics in the classroom and the use of slanted desks in a learning environment. It is amazing how something so simple in concept, is so effective in application and can have such huge benefits. It begs the question: why were slanted desks taken out of the classroom in the first place?  The simple answer is most likely the right one: it was more cost effective. Since flat desks were introduced to the classroom, reading scores have dropped considerably.  European schools are now reintroducing slanted desks in their school classrooms and we too should rethink the ergonomics of learning.

Finally, Sampedro et al. observed the characteristics of the spontaneous reflex reading distance (RRD) in 351 children in two stages, first in reading then writing, and comparing their RRD with the Harmon distance in the same environmental conditions. The results show that 72, 08% of the population analyzed (65% while reading and 53% while writing) had a normal RRD. Also, 50, 96% of people who had too short a RRD were myopic, 38, 46% were emmetropic and 10.58% were hyperopic. Conclusions: the shorter the RRD, the more mental effort is required in near vision; the situation creates more visual stress. So in this study, one third of the children were standing too near their work plan and the RRD was shorter in writing than in reading. More myopic individuals had a tendency to read closer than they should.

  •  Gené Sampedro, Andrés; Montalt, Juan C.; Alemany, Antonio L. Estudio del reflejo visuopostural. Gaceta Óptica, 1997 JUL-AGO; (307)

Posture and Vision (1)

No program that addresses myopia control would be complete without talking about the important concepts of posture and visual hygiene advices.

There is ample evidence that conditions which lead to muscle tension and place undue stress on the visual system will, over a period of time, lead to eye problems such as myopia, and other disorders such as focusing and binocular coordination problems.  Many authorities blame our culture’s emphasis, for both children and adults, upon prolonged near vision tasks (such as reading, writing, drawing, video games, computer work) for an increase in visual problems.

While we cannot eliminate those tasks that need to be done, and may even be pleasurable, they can be carried out in a manner that imposes minimal stress on the visual system.

If followed, these suggestions may result in easier and more productive study and desk work and will have value in preventing or retarding the development of visual problems.

Reading distance

For reading, writing, and other near vision tasks, it is important to read or write at an appropriate distance.

When the working distance is too short, both children and adults, it creates substantial additional effort on the focusing system and alignment of the eyes (convergence) This added stress can lead to eye strain and a which will increase stress symptoms.

The spontaneous distance at which we read is called the reflex reading distance (RRD). This must always be compared to the Harmon distance.

Harmon distance

 In the fifties, D.B. Harmon, an educator and a kinesiologist, has shown that the ideal reading distance for each individual was the distance between the center of the middle joint of the elbow to the center measured outside of the arm. Working at the Harmon distance reduces visual stress at close. Harmon believed that environmental factors were related to the development of visual problems and had an excellent understanding of the relationship between movement, posture and vision.

How to measure Harmon distance

Harmon has conducted studies of posture and vision of a phenomenal number of children (over 160,000!) in the forties and fifties. His main findings were:

  • In 1958 he showed that 30.2% of schoolchildren tested had postural problems that may be related to vision.
  • He had also found an increased prevalence of visual problems with age in children in primary school from 20% at entry to primary school and 80% after five years of school. His investigations in the school environment led him to believe that certain visual problems appeared when subjects were subjected to near vision work in awkward postures in order to maintain an effective visual function. (1958)
  • Poor posture not only causes visual problems. A postural imbalance requires a greater expenditure of energy, which reduces the effectiveness of the subject to perform its task. Thus the child will have a smaller amount of energy for school learning. (1951, 1958) 
  • Harmon also noted that using horizontal surfaces tend to require the student to lean forward and to approach its work plan. It is therefore preferable to use work plans inclined at 10 ° or even better at 20 °.
  • Why 20 degrees? Harmon demonstrates that it is the physiological angle that everyone adopts between the horizontal plane passing through the elbows and forearms while reading, in an unconstrained outdoor environment. This position is accompanied by the facial plane parallel to the plane of the forearms. 
  • When we bend forward to read, this induces cervical stress, makes digestion more difficult and prevents adequate respiration necessary for the proper functioning of metabolism. 

When doing his study, Harmon raised the work-surface to a 20 degree angle, bringing the surface more parallel to the face.  This significantly reduced the compression of the intervertebral discs. See the following image which shows an ideal working posture with a surface tilted 20 degrees.

Ideal working posture 

http://www.visualedgesb.com/

In the fall of 1942, after six months in the remodeled classroom, “only 18.6% of those examined in November showed visual difficulties, as compared with 53.3% tested six months previously.”  There was also a significant reduction of posture problems (reduced by 25%) and chronic fatigue (55%).

It is unfortunate that these studies and conclusions have been relegated to oblivion. Many postural problems and vision could be avoided if we applied simple changes in our schools…

References:

Harmon DB. Notes on a Dynamic Theory of Vision, 3rd Revision. Austin TX, Self Published, 1958.

Harmon DB., Some preliminary observations of the developmental problems of 160,000 elementary school children. Med Woman’s J 1942:49:75-