There was an interesting article in the Economist a couple of day ago: "Why So Many Chinese Children Wear Glasses" (11/9/2014)
Myopia is epidemic in China, and the percentage of those with this affliction is increasing each year.
Here are a few passages from the article that provide food for thought:
The fastest increase is among primary school children, over 40% of whom are short-sighted, double the rate in 2000. That compares with less than 10% of this age group in America or Germany.
The incidence of myopia is high across East Asia, afflicting 80-90% of urban 18-year-olds in Singapore, South Korea and Taiwan. The problem is social rather than genetic. A 2012 study of 15,000 children in the Beijing area found that poor sight was significantly associated with more time spent studying, reading or using electronic devices–along with less time spent outdoors….
The biggest factor in short-sightedness is a lack of time spent outdoors. Exposure to daylight helps the retina to release a chemical that slows down an increase in the eye's axial length, which is what most often causes myopia.
A combination of not being outdoors and doing lots of work focusing up close (like writing characters or reading) worsens the problem. But if a child has enough time in the open, they can study all they like and their eyesight should not suffer, says Ian Morgan of Australian National University
Yet China and many other East Asian countries do not prize time outdoors. At the age of six, children in China and Australia have similar rates of myopia. Once they start school, Chinese children spend about an hour a day outside, compared with three or four hours for Australian ones.
(VHM: emphasis added)
A similar article appeared in the LA Times of 7/5/12: "China's myopia epidemic comes into focus"
"As many as 90% of urban youth in China are nearsighted. Researchers think they can fight myopia by forcing youngsters to put down their books and expose their eyes to natural light."
By the time they complete high school, as many as 90% of urban Chinese youth are afflicted by the condition known as myopia, in which close objects can be seen clearly but things just a few feet or inches away start to blur.
That's about three times the rate among U.S. children. Even more troubling is the severity of the Chinese cases. Between 10% and 20% of nearsighted Chinese children are expected to develop "high myopia," which is largely untreatable and may lead to blindness.
Eight years earlier, a Chinese news outlet focused on the same problem:
"30 Mln Chinese Become Nearsighted Per Year" (7/11/06).
This is not an affliction that has been plaguing generations of Chinese students and adults only in recent years. Very high levels of myopia have been a serious issue in China for a long time. See, for instance, The Ophthalmic Year Book, Volume 18 (1922), p. 49a:
Li's experience convinces him of the necessity for thoro cycleplegia in the great majority of cases. Of a large number of Chinese students examined, 53% were myopic, 36% hyperopic, and 11% showed mixed astigmatism. He ascribes the high percentage of myopia to the peculiar construction of the Chinese characters, writing them being more difficult than reading. Poor hygiene generally prevails among the students.
Rush lists myopia as one of the four chief causes of blindness in China, and states that among students he found 58% were myopic.
(VHM: The studies of Li and Rush appeared in the National Medical Journal of China, 6  and the China Medical Journal, 34 .)
Although myopia rates are lower in rural areas, even there the rate is higher in China than in Australia or the West when the children do have a chance to go to school. In earlier posts on this subject, I commented on the strained, squinting look on the face of Chinese children who are reading and writing.
See item 4 and the photograph of a little girl accompanying it in this post, "The cost of illiteracy in China" (3/31/12), also the photograph of the little boy in this post, "Copying characters" (2/11/13).
Commenting on the photographs accompanying these two posts, I remarked how Chinese children reading and writing often have a strained look on their face. This may due to a variety of factors, including density of strokes, dim lighting, poor printing, and so forth.
There is plenty of anecdotal evidence that would seem to indicate a connection between myopia and Chinese characters, e.g.:
"The reason why so many Chinese have bad eyesight?" (discussion started 12/24/11)
"Reading Chinese characters contributes to myopia" (4/21/09)
Of course, such anecdotal evidence is necessarily inconclusive of a link between myopia and Chinese characters. In searching for scientific studies on the subject, I turned up a few interesting studies.
by D. Xu and W. Xin both from School of optometry and ophthalmology, Wenzhou medical college (Wenzhou)
Purpose This study investigated the effect of simplified and traditional chinese character on accommodative lag, accommodation microfluctuation, near work-induced transient myopia (NITM) during the near task as well as the subsequent decay time. We aimed to analyze if the traditional Chinese character had the trend of inducing the myopia progress.
Methods Young adults were classified into emmetropes and myopes . Two size (12pt,8pt) and two type (simplified and traditional chinese character) were used to give four different reading targets on computer screen. It was presented in random order at 25 cm and was read for 5min. For each target, accommodation response , accommodation microfluctuation NITM and its decay were measured using the free space Grand-Seiko auto-refractor.
Results For myopic subjects, accommodation microfluctuation was greater for traditional chinese character 0.35±0.17 D than for simplified chinese character: 0.29 ±0.11 D, (p=0.017) ,NITM was larger for traditional chinese traditional character 0.61±0.34 D than for simplified chinese character 0.53±0.33 D,p=0.028, however there was no difference in emmetropic subjects. Myopes had larger accommodation microfluctuation 0.35±0.17 D than emmetrope 0.24±0.11 D p=0.02,myopes had greater NITM0.61±0.34 D than emmetropes 0.42±0.25 D P=0.013. For all targets, The accommodative lag of myopes is 0.74±0.32 D while the emmetropes 0.53±0.35 D P=0.000 ;The decay time for myopes was15.88±19.53 seconds while the emmetropes 9.04±12.62 seconds P=0.012.
Conclusion The study showed that compare to the simplified Chinese character, the traditional chinese character had significant effect on myopic subjects, it may be more susceptible of inducing the myopia progress.
This study suggests that, since the density of strokes of simplified characters is less than that of traditional characters, the rate of NITM is greater.
On the other hand, the following study found no significant difference in accommodative responses between traditional and simplified characters, though both resulted in NITM (nearwork-induced transient myopia) after 10 minutes of reading.
Ye YANG; Jin-hua BAO; Jing-jing XU; Chen-xiao WANG; Fan L(U)
Chinese Journal of Experimental Ophthalmology 2012; (12) : 1100-1103
Background Epidemiologic studies found that the incidence of myopia is higher in Hong Kong and Taiwan regions of China than that of the mainland. So whether the general reading words with traditional Chinese characters and simplified characters is associated with myopia deserves attention. Objective This study was to test the accommodative responses and the regression levels of nearwork-induced transient myopia (NITM) induced by traditional complex Chinese characters and modern simplified ones in the same size, and to explore the differences and inherent relationship of the accommodative regulations based on the structures of the two types of Chinese character in causing reading triggered myopia. Methods Twenty two volunteers aged 24-29 years were included in this study with informed consent. The corrected vision of both eyes from each subject was ≥ 1.0 with a mean spherical equivalence of (-1.86±2.34)D. Accommodative response was tested with 4 different reading texts using the rapid sequence visual presenting model with the GRAND SEIKO-WV5500 infrared autorefractor, and this procedure was performed after full correction of refractive error. An initial test of looking at a certain distance was performed (as baseline), and then the subjects read intensively at the targets for 10 minutes at 33 cm to calculate the accommodative responses. After a 10 second pause, the ocular refractive status was obtained exactly at 15 seconds, 20 seconds. The one-way ANOVA method was used to determine the effects of the different font types and sizes on the adjustive responses and the causation of NITM. Results Accommodative response induced by simplified and traditional Chinese characters showed an accommodative lag of (1.11 ±0.38),(0.95 ±0.43),(1.18 ±0.33) and (1.06±0.28) D,showing a significant difference among the 9 pt and 12 pt simplified and traditional Chinese characters (F =1.62,P =0.19), and significantly different accommodative lag values between 12 pt simplified characters and 9 pt traditional characters was found (t =5.56,P =0.02). NITM induced by the four different targets were (-0.45 ±0.45), (-0.47 ±0.46), (0.45 ±0.82) and (-0.46±0.78) D in the 4 types of characters, without a significant difference among them (F=0.01,P =0.99). Conclusions Near-distance reading causes accommodative lag regardless of the type of reading texts.The target demonstrated stimuli spatial frequency and font size play an impact on accommodative responses. NITM appears when one reads simplified or traditional Chinese for 10 minutes. The accommodative lag and NITM trend might be responsible for the onset or regression of myopia, yet it is not supportive for the hypothesis that reading traditional Chinese causes more strain since there is no difference between the two.
(VHM: emphasis added)
The last two cited studies only indicate that both simplified and traditional Chinese characters cause NITM, but that there is no significant difference between them.
The biggest breakthrough in my research on the subject of the relationship between Chinese characters and eyestrain came from an unexpected source, this compelling article in Mutant Palm:
Among other insightful observations and valuable data proffered, Dave Lyons (the guy behind Mutant Palm) states:
In one study, rates of myopia in Chinese peasants were found to be around 5%, while scholars had nearly 85%. A study in Taiwan found that older Chinese people and older white people had comparable rates of myopia, but younger Chinese had it far more than younger whites. All of this suggests that with increased literacy and reading in China comes myopia.
As Lyons remarks, written Chinese clearly involves more nearwork than written English. He cites a recent post by Chinese blogger Hecaitou that provides a compelling example of this. It comes from an “Alzheimer’s Test” that has three questions like this one:
This is a REAL neurological test. Sit comfortably and feel calm.
Find the C below. Do not use any cursor help.
I found the "C" within one or two seconds, and most of the commenters easily found the C.
Now look for the yǐ 已 ("already") amidst all the jǐ 己 ("self; sixth heavenly stem") in the following sample (I won't trouble you with throwing in an occasional sì 巳 ["sixth earthly branch"]):
己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己 己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己 己己己己己己己己己己己己己己己己己已己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己 己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己 己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己 己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己 己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己己
Not only is this a myopia inducing exercise, it is also apt to bring about cephalalgia.
Commenter EGG suggests a pair of characters with more strokes: gǎo 搞 ("do; make; care; get; start; get hold of; participate; go in; produce; set up") and gǎo 稿 ("draft; manuscript; sketch; stalk of grain; straw") — with 13 and 15 strokes respectively, 搞 and 稿 have just above the average number of strokes for a Chinese character, which is around 12.
稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿 稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿 稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿搞稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿 稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿 稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿稿
You will be forgiven if you were not so persistent as to find the 已 and the 搞 among the masses of 己s and 稿s.
I love the way Lyons ends his article: "Perhaps the incidence of myopia in China would be reduced if text were segmented. I wonder what John DeFrancis would say." I'm sure that my old friend JDF would have heartily applauded such a move.
Just before the concluding section of his article, however, Lyons introduces us to Gord Hotchkiss's fascinating piece entitled "Chinese Eye Tracking Study: Baidu Vs Google" (6/15/07), which presents striking heat map comparisons.
Judging from eye scans and mouse clicks, Baidu searches are much more scattered, inefficient, and relatively unsuccessful, whereas Google searches are more patterned, efficient, and comparatively successful.
From all of the materials assembled above, it would appear that Chinese reading and writing require more nearwork and eyestrain than are needed for reading and writing with the Roman alphabet. Chinese teachers are well aware of the burdens placed upon their students and the consequent deterioration of vision. So they resort to all sorts of measures to alleviate the detrimental effects of reading and writing characters, such as:
"New eye exercises for Chinese students, but just as useless as before" (11/29/08) and desk railings to keep their students from getting too close to their books and papers!
The good doctor Ian Morgan of Australian National University, who is cited in some of the above articles, insists that Chinese students wouldn't have such a high incidence of myopia if only they would go outdoors more often. That makes a lot of sense. The questions is, though, why don't Chinese school children spend more time outdoors? Perhaps it's because they want to master those high maintenance characters, and to do so requires writing each one of them hundreds and hundreds of time so that one can recognize them accurately and reproduce them correctly when called upon to do so in tīngxiě 听写 ("dictation" [lit., "hear-write"]) quizzes.
It's a series of vicious cycles and circles: the further those railings keep the children from their books and papers, the harder they strain to distinguish the tiny strokes on them; the more time the children spend outside playing, the poorer they do on their character quizzes. Somehow, a balance needs to be struck between the demands for literacy and the need for good eyesight.