Myopia more prevalent in middle-income school childrenMiddle-class children in China are twice as likely to be short-sighted than their lower-income peers, according to a new large population-based study.
In a study of almost 20,000 school-aged children in two regions of Northern China, the largest of its kind, researchers found that myopia was less prevalent among lower-income students.
Research from 2012 reported that Asia is experiencing an ‘epidemic’ of short-sightedness, with up to 90% of young adults in major East-Asian countries estimated to have myopia, including 50% of China’s one billion plus population. This has led to some schools taking extreme preventative measures, such as primary schools installing bars on the desks to stop students from working too close to their desks.
In 2012 the Chinese government agencies and universities collaborated with researchers from Stanford University in the US to conduct the largest population-based study to date. They looked at almost 20,000 fourth and fifth graders in two provinces; middle-income Shaanxi province, and the neighbouring, lower-income, Gansu province.
Among the cohort of 9,489 students from the middle-income Shaanxi province, an estimated 23% had myopia. But in neighbouring Gansu, the rate fell to just 12.7% of the cohort of 10,137 students. The study also found that living in a middle-income area was associated with a 69% increase in the risk of myopia.
Overall, the research found that myopia was less prevalent in males, and that higher maths scores were associated with myopia in all children. It is unclear whether the use of blackboards, which feature more prominently in teaching methods in the lower-income region, plays a role. The researchers suggest that the widespread use of text books in the middle-income regions may lead to more close-up work by students, which may increase myopia, and that distance focus required for students using blackboards may offer a protective effect.
Lead investigator of the study, Professor Nathan Congdon, of the Zhongshan Ophthalmic Centre at Sun Yat-sen University, said: “We’re still on the hunt for a plausible explanation and think the results merit more study into whether using blackboards versus books may be particularly responsible for protecting eyes against nearsightedness, and what other factors may play a role.”
The findings are published in Ophthalmology.
(TAKEN FROM OPTOMETRY TODAY www.optometry.co.uk)