Around 80% to 90% of school-leavers in major East Asian cities likeChina, Taiwan, Hong Kong, Japan, Singapore and South Korea sufferfrom myopia or short-sightedness. This represents an enormous burden of disease that will lead tofurther problems in the future, as 10 to 20% of those affectedsuffer from 'high' myopia that can ultimately lead to loss ofvision, impaired vision, as well as blindness. Professor Ian Morgan, from the Australian Research Council Centreof Excellence in Vision Science, and the Australian NationalUniversity in Canberra, and team report in the second paper in The Lancet Series on Ophthalmology that this extremely high prevalence of myopia is linked toincreased schooling, according to recent data, which indicates thatthe lack of daylight exposure could have a major impact on thisgigantic problem. It was previously believed that myopia was mainly based ongenetics.
However, more recent evidence shows that environmentalfactors are involved as well. For instance, the three key ethnicgroups in Singapore, i.e. Chinese, Indians and Malays have allexperienced steep increases since 1996, indicating a similarsensitivity to the risk factors they were all exposed to. Migrant studies have also proved crucial as they revealed that inthe UK and Australia children of South Asian ancestry have a higherprevalence of myopia compared with those in India, although not ashigh as compared with those in Singapore.
In Australia for instance, students of Chinese origin have lowerlevels of myopia compared with those in urban centers in East andSoutheast Asia, whilst the number of children of European origin inSydney with myopia is less than half of those in the UK. Numerous studies have demonstrated that an association existsbetween schooling and myopia, with reading books close-up andintensive study having been determined as the causes of myopia.According to more recent epidemiological surveys, longer periodsoutdoors protect against developing myopia. A similar study ofchildren from Chinese ancestry from Singapore and Sydney hasdemonstrated that the only environmental factor that correlatedwith the significantly higher prevalence of myopia in Singapore wasthe time spent outdoors. To examine the impact of higher outdoor exposure as a preventivemeasure, Singapore and China are currently undertaking trials.These studies demonstrate that the causes of ethnic differences inschool myopia are children's different experiences at differentplaces, and not ancestry genetics. Outdoor Led Flood Lights
However, it remains to bedetermined to what extent many genes of small effect andgene-environment interactions contribute to variations in schoolmyopia within ethnic groups. Furthermore, even though theoccurrence of high myopia is increasing because of environmentalpressures, some forms of high myopia have a more distinct geneticbasis. The researchers point out that various trials of optical aids, suchas contact lenses and spectacles can help in preventing myopia orits progression. These optical devices include lenses that canneutralize peripheral hyperopic errors, or impose localized myopicdefocus, although the team add that prolonged use of these devicesleads to a reduction or disappearance of the device's protectiveeffects. China Led High Bay Lighting
They caution doctors to delay widespread use of any ofthese devices until the results from long-term trials, includingtheir side effects are published. Atropine, which is frequently used in East Asia, is well known toslow progression of myopia in children. However, it has not beenadopted on a larger scale because of its side effects. According torecent evidence, lower doses were likely to be result in a positiveeffect, outweighing the drug's side effects, which could lead tomore clinicians using the drug. China Flat Panel Led Lights
The researchers state that further research needs to be conductedin order to identify methods to prevent myopia from progressinginto high myopia. They highlight that those affected should beaware of the condition's potential risk of eventual blindness, andshould immediately seek treatment. The researchers conclude: "Even if successful prevention is possible, east Asia will still befaced, for close to the next 100 years, with an adult population athigh risk of developing pathological [high] myopia. Furtherprogress in our understanding of the natural history ofpathological myopia is thus essential, and while there have beensome promising developments in treatment, more effective treatmentsare still required." Written by Petra Rattue Copyright: Medical News Today Not to be reproduced without permission of Medical News Today Additional References Citations.
However, more recent evidence shows that environmentalfactors are involved as well. For instance, the three key ethnicgroups in Singapore, i.e. Chinese, Indians and Malays have allexperienced steep increases since 1996, indicating a similarsensitivity to the risk factors they were all exposed to. Migrant studies have also proved crucial as they revealed that inthe UK and Australia children of South Asian ancestry have a higherprevalence of myopia compared with those in India, although not ashigh as compared with those in Singapore.
In Australia for instance, students of Chinese origin have lowerlevels of myopia compared with those in urban centers in East andSoutheast Asia, whilst the number of children of European origin inSydney with myopia is less than half of those in the UK. Numerous studies have demonstrated that an association existsbetween schooling and myopia, with reading books close-up andintensive study having been determined as the causes of myopia.According to more recent epidemiological surveys, longer periodsoutdoors protect against developing myopia. A similar study ofchildren from Chinese ancestry from Singapore and Sydney hasdemonstrated that the only environmental factor that correlatedwith the significantly higher prevalence of myopia in Singapore wasthe time spent outdoors. To examine the impact of higher outdoor exposure as a preventivemeasure, Singapore and China are currently undertaking trials.These studies demonstrate that the causes of ethnic differences inschool myopia are children's different experiences at differentplaces, and not ancestry genetics. Outdoor Led Flood Lights
However, it remains to bedetermined to what extent many genes of small effect andgene-environment interactions contribute to variations in schoolmyopia within ethnic groups. Furthermore, even though theoccurrence of high myopia is increasing because of environmentalpressures, some forms of high myopia have a more distinct geneticbasis. The researchers point out that various trials of optical aids, suchas contact lenses and spectacles can help in preventing myopia orits progression. These optical devices include lenses that canneutralize peripheral hyperopic errors, or impose localized myopicdefocus, although the team add that prolonged use of these devicesleads to a reduction or disappearance of the device's protectiveeffects. China Led High Bay Lighting
They caution doctors to delay widespread use of any ofthese devices until the results from long-term trials, includingtheir side effects are published. Atropine, which is frequently used in East Asia, is well known toslow progression of myopia in children. However, it has not beenadopted on a larger scale because of its side effects. According torecent evidence, lower doses were likely to be result in a positiveeffect, outweighing the drug's side effects, which could lead tomore clinicians using the drug. China Flat Panel Led Lights
The researchers state that further research needs to be conductedin order to identify methods to prevent myopia from progressinginto high myopia. They highlight that those affected should beaware of the condition's potential risk of eventual blindness, andshould immediately seek treatment. The researchers conclude: "Even if successful prevention is possible, east Asia will still befaced, for close to the next 100 years, with an adult population athigh risk of developing pathological [high] myopia. Furtherprogress in our understanding of the natural history ofpathological myopia is thus essential, and while there have beensome promising developments in treatment, more effective treatmentsare still required." Written by Petra Rattue Copyright: Medical News Today Not to be reproduced without permission of Medical News Today Additional References Citations.