Upon coming to China, it is a common thought for the new arrival that a lot of Chinese people apparently need to wear glasses, more so than in other countries. It would also be normal to wonder whether this might be an illusion; that a smaller proportion of the population choose contact lenses. The initial observation turns out to be correct. The Chinese are a myopic race. In fact, one and a half times more so than the world on average; 33 percent versus 22 percent.
This has in turn, created a colossal market for eyewear. While accurate figures are very hard to come by, EuroMonitor valued the Chinese eyeglasses market in 2015 at ¥67.9 billion. Contact lenses accounted for another 4.2 billion while both sectors see growth of 10 percent.
There is a town called Danyang, close to Nanjing, of approximately one million people, that is home to China’s optic industry. Here, as much as 10 percent of the local workfare is engaged in the production of eyeglasses.
Danyang is one of China’s four centres for eyeglasses. For the optically impaired, the China (Danyang) International Glasses City is delightfully also only 25 minutes, or ¥44.5, by high speed train, from Nanjing South Railway Station and lying adjacent to Danyang railway station itself.
Unlike the other three, the Danyang operation is mainly focused on domestic sales. Herein, over 600 Small and Medium Sized Businesses are engaged in the production of eyeglasses, employing close to 100,000 people (getting on for 10 percent of the local population) in what is the largest spectacles trading market in China.
The figures are astronomical. Yet, they stop us from asking the bigger question. Just why are the Chinese so myopic?
Delve deeper and among young people it is found that the myopic rate is at its highest amid senior high school students, at 85 percent.
Not surprising then, that until as recently as last year, the popular consensus was the pervasive nature of study in Chinese society; too much time staring at a book cannot possibly be good for one’s eyes. Yet, it is not only China; myopia is on the rise the world over. Again, study was assumed to be the culprit in our ever more competitive world.
The global rise of the smartphone has also been linked to the increase in myopia, while in China specifically, research has shown that as much as 67 percent of children start their relationship with electronic products aged 4. The blue light emitted from such devices is a big cause for concern among Chinese parents, one that has led to a whole new market in spectacles with blue light blocking lenses.
Now, however, a growing body of evidence has emerged that suggests the large occurrence rate may, in fact, have little to do with study or smartphones, and more down to the fact that many Chinese spend long periods indoors in poor lighting conditions. For decades, Chinese homes have had bad lighting; a single low wattage bulb hanging overhead providing the illumination for that all-important study.
The new findings show that it is the level of light received by the eye, not what the eye is doing, that contributes to the growth in myopia.
Enter the “light-dopamine” theory. The increase in light intensity as a result of being outside, it is proposed, can stimulate the release of dopamine (dihydroxyphenethylamine) in the eye. In turn, the neurotransmitter can block the axial elongation of the eye as it develops, particularly among children.
In order for the dopamine to be released, light levels need to be high. Really high. Typical light levels in an office space are 50 lux. Outside, a gloomy overcast day might reach 80 lux. For the eye to get the hit of light it needs to trigger the dopamine, light levels need to be of the order of 10,000 lux. This is about the level experienced by someone under a shady tree, wearing sunglasses, on a bright summer day.
The logical first step is simply to step outside more often.Yet, encouraging children to spend more time outdoors is more difficult than one might imagine. Experience in Singapore shows us that parents are unlikely to act on the information that being outside more is good for their children’s eyesight.
Professor Ian Morgan, of the Research School of Biology, Australian National University, Canberra, and the Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, spoke at length with The Nanjinger about his epidemiological studies that estimate children should spend approximately three hours each day in light levels of at least 10,000 lux in order to be protected against myopia.
“The situation with regard to myopia is too serious to wait for people to take voluntary action, give the long-standing emphasis in China on education as the pathway to success in life… [The] introduction of mandatory targets for time outdoors within school time makes a lot of sense, because that means that parents cannot avoid them. If such measures were particularly targeted at preschools and primary schools, that would ensure that all kids were getting enough outdoor time, with less study pressure, at critical ages”, commented Morgan.
The professor went on to highlight a program underway in Taiwan whereby children spend 2 hours per day outside in school time that does initially appear to be working in bringing the myopia rate down; “They introduced ‘Tian Tian 120’ in 2010, and since then children’s vision has been getting better. But there is still a long way to go.
“There are two issues with myopia. The first is to stop it appearing at all, which is where outdoors comes into play. Generally, myopia gets more severe as the kids get older, and the second is therefore to slow that is called myopia progression to stop the kids becoming highly myopic. There are now quite effective ways to do this, with eyedrops or special glasses. A school-based system of annual vision checks would ensure that kids get prompt referral to clinicians, to assess their risk of becoming highly myopic and to start treatment if necessary.”
While the benefits of outdoor learning have been well documented, our particular climate in Nanjing presents numerous challenges. Not only are there numerous days each year where schools are forced to keep children inside on account of AQI levels, the Nanjing sun is nothing short of ferocious for a good portion of the year. For this very reason, Professor Morgan and colleague Nathan Congdon are putting forward proposals for glass classrooms. With China’s policy framework actually very positive on the issue of myopia, the pair are actively looking for funding for a school-based clinical trial to test whether they really work.
Yet, before our schools begin to resemble botanical gardens, the concept raises enormous challenges in other areas; the interior of a car during the height of Nanjing’s summer can top 60 degrees Celcius. Glass classrooms would require unimaginable amounts of air conditioning and a horrific resultant electricity bill. At the other end of the spectrum, the same greenhouse effect would produce considerable savings on heating during the cooler months.
This, of course, is all some way off, if and when the light-dopamine theory is proved correct. Without a universal standardised method of assessment, which produces comparable results across racial, cultural, and geographical boundaries, there is scope for systematic bias influencing results. The quality of data and accuracy of assessment can be affected by many factors, such as definitions of near work, validation of the questionnaire, training of the interviewer, and recall bias.
Until such times, as living standards improve, Chinese consumers will continue to attach greater importance to the health and protection of their eyes when choosing spectacles, and more and more people will be buying glasses of higher quality.
For the good people of Danyang, putting rice on the family table is likely to not be a worry, as the business of myopic cures looks set to remain very lucrative for the world’s largest group of spectacle wearers.
