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Archive for the ‘Myopia progression’ Category

More evidence that outdoor time may help prevent nearsightedness

Kids who spend more time outdoors and who play sports are less likely to be near-sighted, according to a recent study in a large, diverse group of urban 6-year-olds.

“Lifestyle in early youth is very much associated with onset of myopia,” says Dr. Caroline Klaver of Erasmus Medical Center in Rotterdam.

“Not being outside, and performing lots of near work will increase risk a lot.”

While factors like being highly educated and of non-European heritage have traditionally been linked to nearsightedness, the new study suggests that how young children spend their time is likely to be the underlying source of these differences, the study team writes in the British Journal of Ophthalmology.

The researchers looked at 5,711 children in Rotterdam who have been participating since birth, along with their mothers, in a long-term study. At age 6, prevalence of myopia was 2.4% (n=137). Myopic children spent more time indoors and less outdoors than non-myopic children (p<0.01), had lower vitamin D (p=0.01), had a higher body mass index and participated less in sports (p=0.03).

The researchers used statistical techniques to analyze a wide variety of factors, including social and economic aspects of the household, ethnicity, lifestyle, parents’ education levels, children’s’ activities and any links between these and the likelihood a child would be nearsighted.

The study team found that myopic children spent less time outdoors, had lower levels of vitamin D, had a higher body mass index and were less likely to play sports than children who weren’t nearsighted. While being of non-European descent, having a mother with a low education level and low family income were also associated with myopia, the researchers found that lifestyle factors explained most of these risks.

The study was limited by the low number of children with myopia and the lack of information about parents’ nearsightedness – “a well-known myopia risk factor,” the authors note.

“Differences in myopia prevalence between ethnic groups that have commonly been assumed to be down to genetics may in fact be due to differences in lifestyle between ethnic groups,” Dr. Jeremy Guggenheim, an optometry professor at Cardiff University in the UK, told Reuters Health in an email.

“The new study and other recent work suggests that this preventative effect of time outdoors is beneficial even at very young ages, e.g. 3 – 6 years-old,” said Guggenheim, who studies the causes of myopia and sometimes collaborates with Klaver’s team, but was not involved in the current study.

“Too much close work, such as reading and using hand-held devices, may also be a risk – although the jury is still out on this question,” he added.

To help prevent myopia, Klaver said, parents should have children play outside for 15 hours a week, and limit “near work” to no longer than 45 continuous minutes.

“It’s important to keep in mind that this type of study can never pin-point the precise causes of myopia in the way that is possible using purpose-designed clinical trials,” Guggenheim said. “Nevertheless, the risk factors that were identified in the new study fit neatly with what has been learned in recent years from such trials.”

“Basically this study adds very nicely to the evidence that we already see from many other studies and many other countries that there is definitely a connection between outdoor activity and myopia in children,” said Susan Vitale at the U.S. National Eye Institute.

“The main thing to remember is that if parents have any concerns about their child’s vision it’s very important that they get a dilated eye exam from a health care professional,” Vitale said. Regular eye care is the most important thing people can do to maintain their eye health, she added.

(Reuters Health)

Pictures: https://commons.wikimedia.org

SOURCE: Tideman JWL, Polling JR, Hofman A, Jaddoe VW, Mackenbach JP, Klaver CC. Environmental factors explain socioeconomic prevalence differences in myopia in 6-year-old children. Br J Ophthalmol. 2017 Jun 12. pii: bjophthalmol-2017-310292. doi: 10.1136/bjophthalmol-2017-310292.

Other studies have also looked at the relationship between time outdoor and myopia (and many more…):

• Wu PC, Huang HM, Yu HJ, Fang PC, Chen CT. Epidemiology of Myopia. Asia Pac J Ophthalmol (Phila). 2016 Nov/Dec;5(6):386-393.

• Deng L, Pang Y. The role of outdoor activity in myopia prevention. Eye Sci. 2015 Dec;30(4):137-9.

• Isaacs D, Wood N. Let’s not be short-sighted: Increased outdoor activity reduces myopia. J Paediatr Child Health. 2016 Oct;52(10):969. doi: 10.1111/jpc.13358.

• Suhr Thykjaer A, Lundberg K, Grauslund J. Physical activity in relation to development and progression of myopia – a systematic review. Acta Ophthalmol. 2016 Dec 14. doi: 10.1111/aos.13316.

• Guo Y, Liu LJ, Tang P, Lv YY, Feng Y, Xu L, Jonas JB. Outdoor activity and myopia progression in 4-year follow-up of Chinese primary school children: The Beijing Children Eye Study. PLoS One. 2017 Apr 27;12(4):e0175921. doi: 10.1371/journal.pone.0175921. eCollection 2017.

 

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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.

Researchers recommend increasing time spent outdoors during school

Photo JPL-blogueDecidedly, 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

Photo JPL-blogueRecently, 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/

Multifocal Contact Lens Myopia Control

Photo JPL-bloguePrevious studies on soft multifocal contact lens myopia control published in the peer-reviewed literature reported findings of noncommercial contact lenses worn for 1 year or less. This study sought to determine the progression of myopia and axial elongation of children fitted with commercially available distance center soft multifocal contact lenses for 2 years.

Eight- to eleven-year-old children with −1.00 D to −6.00 D spherical component and less than 1.00 D astigmatism were fitted with soft multifocal contact lenses with a +2.00 D add (Proclear Multifocal “D”; CooperVision, Fairport, NY). They were age- and gender-matched to participants from a previous study who were fitted with single-vision contact lenses (1 Day Acuvue; Vistakon, Jacksonville, FL). A-scan ultrasound and cycloplegic autorefraction were performed at baseline, after 1 year, and after 2 years. Multilevel modeling was used to compare the rate of change of myopia and axial length between single-vision and soft multifocal contact lens wearers.

Forty participants were fitted with soft multifocal contact lenses, and 13 did not contribute complete data (5 contributed 1 year of data). The adjusted mean ± standard error spherical equivalent progression of myopia at 2 years was −1.03 ± 0.06 D for the single-vision contact lens wearers and −0.51 ± 0.06 for the soft multifocal contact lens wearers (p < 0.0001). The adjusted mean axial elongation was 0.41 ± 0.03 and 0.29 ± 0.03 for the single-vision and soft multifocal contact lens wearers, respectively (p < 0.0016).

Soft multifocal contact lens wear resulted in a 50% reduction in the progression of myopia and a 29% reduction in axial elongation during the 2-year treatment period compared to a historical control group. Results from this and other investigations indicate a need for a long-term randomized clinical trial to investigate the potential for soft multifocal contact lens myopia control.

Source: Walline JJ, Greiner KL, McVey ME, Jones-Jordan LA. Multifocal contact lens myopia control. Optom Vis Sci. 2013 Nov;90(11):1207-14. doi: 10.1097/OPX.0000000000000036.

 

 

Myopia: a world tour

Photo JPL-blogueThe 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.

Myopia

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.

Vie rurale et urbaine

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.


Singapour

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