"Doctor, I forbid children to watch TV and take them outdoors on holidays. Why is he/she myopic? "Myopia, is it real or pseudomyopia? Does he/she need to wear glasses? A barrage of questions are fired by anxious parents at the clinic.

Myopia has become the number one enemy that affects the visual health of school children, and it has also cast a shadow over parents’ expectation of their children.

According to a survey published by the Ministry of Education at the end of 2000, the proportion of myopia among elementary school children in Taiwan is 20% in grade one, 60% in grade six, and 85% in university. It can be said that almost all students are myopic. This high prevalence of myopia has made Taiwan the number one in the world dubbed the "island of myopia."

The refractive state of the eyeball depends on the combination of the tortuosity of the eyeball (cornea plus lens) and the length of the anterior diameter (axis length) of the eyeball. Except for a few cases of congenital myopia, most of the children are hyperopia. With the development of the eyeball, hyperopia decreases and myopia develops. If the length of the optic axis increases continuously, myopia will occur.

The myopia in domestic school children is mostly caused by the increase of the eye axis. The length of the normal optical axis is about 23-24 mm. An increase in the axial length of 1 mm causes a myopia of about-3.0 D. In high myopia of -6.0 D or above, with the worsening of near-sightedness, the eyeball will continue to lengthen backwards, which is prone to eyeball damage, such as synchysis, early occurrence of floaters, retinal thinning and degeneration, degenerative holes, retinal detachment, macular hemorrhage, and posterior polar chorioretinal degeneration. Glaucoma and early cataract are also more likely to occur, which will affect the health and vision of the eyes.

Why does the growth of the eyeball lead to the worsening of myopia?

The real pathogenesis is still unclear. At present, the more accepted hypothesis is the balloon theory and the imaging theory. The former is that the eyeball will be blown up like a balloon because of the changes of the intraocular pressure from near-range accommodation and squinting. The degree of the change depends on the strength of the blow and the strength of the scleral wall resistance of the eyeball. The latter refers to the fact that unclear retinal images may cause the eyeball to produce some growth factor that promotes scleral growth. Both of them have evidences in animal experiments and clinical observations, and may be correlated to each other.

With the development of urban environment and concrete jungle, coupled with parents worried that their children might be at a disadvantage, children have to attend different preschool classes and countless near work, such as reading, writing, playing the piano, using the abacus and computer. Misuse of our eyes from childhood results in a prize on everyone's nose – a pair of spectacles. In particular, the younger the age, the greater the plasticity of the sclera, the longer the optical axis becomes. The younger when children suffer from short sight, the faster it will worsen, the more difficult it will be to control, the greater the chance of deteriorating into a high myopia, the greater the damage to the eyeball.

I can't help but think that our predecessors forced their daughters to have their feet bound as children, thinking that bound feet was beautiful, while nowadays, we parents want our children to be better than others, to learn more than others, and neglect the fact that abusing their eyes too early and excessively may cause eye injury. That's the pot calling the kettle black.

The most important thing to prevent myopia is to avoid abusing our eyes from childhood.

Too early learning, too much near work, poor environment, long time watching TV, operating computers and playing video games are all killers of destroying children's eyesight.

• Let children see more than 6 meters away.

Be engaged in outdoor activities such as flying kites, riding bicycles, and playing balls, which not only relaxes their ciliary muscles and avoids myopia, but also improves their physical fitness and health.

• A balanced diet

Appropriate intake of vitamins such as A, B, C and E and minerals such as calcium and iron can strengthen the sclera and slow down the increase in the length and the eye axis and the worsening of the vision.

The goal of correcting myopia

To provide enough visual acuity for daily work and learning, and to delay the worsening of the vision, avoid higher myopia associated with ocular comorbidities.