MYOPIA EPIDEMIC

As levels of myopia continue to rise to epidemic proportions in China and other parts of East and Southeast Asia, there is growing evidence that education and behaviour may have a greater impact on the development of near-sightedness than do genetic factors.
With each school year completed a person becomes more near-sighted, and the higher the level of education completed, the more severe the impairment of vision, according to the results of a major population-based cohort study of myopia carried out at Mainz University Medical Centre, Germany.
While nearsightedness is widespread, it has become more prevalent around the world in recent years and presents a growing global health and economic concern, said Professor Norbert Pfeiffer who led the research along with Dr Alireza Mirshahi. 
To analyse the possible correlation between myopia development and education, researchers at the Mainz University Medical Centre examined myopia in 4,658 persons from mid-western Germany aged 35 to 74 years, excluding those who had undergone cataract or refractive surgery. 
Undertaken as part of the Gutenberg Health Study, the results demonstrate that myopia becomes more prevalent with a higher level of education. Only 27 per cent without any school graduation were myopic, while 51 per cent of high school graduates were nearsighted. In contrast, no less than 53 per cent of university graduates were nearsighted.
In addition to education levels completed, the Mainz-based researchers found that people who spent more years in school tended to be more myopic, with nearsightedness worsening for each year of school. The researchers also looked at the effects of 45 genetic markers, but found that these have a much lower impact on the severity of nearsightedness compared to the level of education achieved.

special spectacles
The researchers note that attempts to slow the progression of myopia with special spectacles or contact lenses have proved unsuccessful or impractical to date. And while some studies have shown low-dose atropine eye drops to be effective in controlling myopic progression, issues of compliance, cost and concerns about possible long-term side effects may limit their widespread adoption.
One possible solution, however, may be simply to encourage children to spend more time outdoors, with a number of large-scale studies now showing that the risk of the development of myopia may be less with spending more time outdoors and, thus, by greater exposure to sunlight and greater time looking at the far. 
Around 15 hours per week appears advisable, according to the Mainz University press release, while at the same time the eyes should not be used for close-up activities such as reading or using computers and smartphones for more than 30 hours per week. 
The findings of the Mainz University research broadly echo two separate landmark studies in recent years, in which Donald Mutti and colleagues at Ohio State University and an Australian group led by Kathryn A Rose and Ian G Morgan from the University of Sydney and the Australian National University first highlighted the link between environmental factors and myopia development.   
“Kathy Rose and I challenged the dogma that myopia was genetic in a major review published back in 2005,” Prof Morgan, Research School of Biology at the Australian National University, Canberra, told EuroTimes. 
“In 2008 we reported on the data we had been collecting on time outdoors as a protective factor. I have to say that we are happy that the evidence since then has increasingly confirmed our, at the time, quite heretical hypotheses. This new paper by Mirshahi and colleagues gives the importance of environmental factors very strong support,” he said.
Prof Morgan noted that while the prevalence of myopia does appear to be increasing in Europe, it is still quite a bit lower than in East Asia, where young adults are now 80-90 per cent myopic, and where the level of high myopia is now of the order of 20 per cent, compared to around one to three per cent in Europe. 
“The detailed genetic studies that have been carried out have so far not found any genetic factors to be associated with the much higher prevalence of myopia in East Asia. But we now know of two factors that are important in generating the difference. The first is the massive educational demands on children in East Asia, who effectively start studying for competitive university entrance from the beginning of primary school, if not earlier. The other factor is the amount of time that children spend outdoors, which appears to prevent the development of myopia,” he said.
Prof Morgan said that the available survey data suggest that children in East Asia spend remarkably little time outdoors compared to children in Europe, North America or Australia. 
The evidence is finally prompting health authorities and governments in the countries most affected by the upsurge in myopia to take action to counteract the phenomenon, said Prof Morgan.
Singapore, for instance, has officially adopted more time outdoors as its myopia prevention strategy, but is approaching this by attempting to influence parental choices through information campaigns. The Chinese government is also currently discussing whether to severely limit the amount of homework given to children in kindergartens and primary schools.

Alireza Mirshahi: alireza.mirshahi@unimedizin-mainz.de
Norbert Pfeiffer: pfeiffer@augen.klinik.uni-mainz.de
Ian Morgan: ian.morgan@anu.edu.au