Changzhi city in Shanxi province is planning to make myopia and obesity part of the criteria for passing the high school entrance examination.

Those with perfect vision will get five points, those with medium myopia four, and those with acute myopia three points. Similarly, those with lower body mass index will get more points than those with higher ones. The local authorities said they want to encourage middle school students and their parents to pay more attention to health. Though the intention is good, whether it will achieve the desired results is debatable.

Myopia and obesity are not always linked to a child's habits; genes also play a part. Two students might be studying for the same length of time under the same light conditions every day, but only one of them might develop myopia. Those 3-5 points could unfairly cost the student with myopia his seat. The authorities in Changzhi say they will take congenital myopia into consideration, but that may not be enough.

Second, it is not the responsibility of parents alone to ensure their wards don't develop myopia. There is widespread consensus among ophthalmologists that lack of outdoor activity is the main factor causing myopia in young people, because the eyes get easily tired staring at short distances, while lack of exposure to sunlight leads to deficiency of vitamin D, which is good for the eye.

Too much homework and overuse of electronic gadgets such as smartphones and tablets also push up myopia rates in children. Schools can address two of these three causes by arranging for more physical exercise classes and giving less homework. At home, the parents can encourage students to sleep early and not spend too much time on electronic gadgets.

Education authorities should consider asking schools to limit homework and increase the time students spend on outdoor activity, instead of passing the responsibility on to parents.