Myopia, commonly known as nearsightedness, is a major problem in East Asia, with somewhere between 80 to 90 percent of the population affected by this condition. The problem is especially prevalent in China. Half of the world’s 13 million children with myopia reside in this country. To find the cause behind these statistics, a recent study looked into myopia among children in two Chinese provinces and produced perplexing results.
The study was conducted in 2012 by government agencies and universities in China, along with scholars from Stanford University. They studied the vision of 9,489 students in Shaanxi, a middle-class province, and 10,137 students in Gansu, one of the poorest provinces in the country. The results were somewhat surprising. Myopia was found in 23 percent of students in Shaanxi and only 12.7 percent of students in Gansu.
Why would students from middle-income families have twice the risk for myopia than those from lower-income families? The researchers are still looking to pinpoint the main cause, but they do have one plausible theory: blackboards. Students residing in Gansu likely rely more on blackboards in the classroom than textbooks. Textbooks require up-close focusing that been linked to myopia in other studies. Other than that, researchers could not find any differences between the two provinces that might explain the variation.
Here are three more interesting findings from the survey:
• Myopia was less prevalent in males than females.
• When adjusting for other factors, living in a middle-class area resulted in a 69 percent increased risk for myopia.
• There was a direct correlation between higher math scores and myopia in all children.