Myopia is a type of refractive error. An object can only be seen clearly if it falls on the retina, which requires a sensitive adjustment of structures such as the lens in the eye. If the lens is overly regulated, the lens becomes excessively convex and does not return to its original shape, or even if the anterior and posterior diameters of the eye are too long, the light from distant objects refracted by the lens will fall on the front of the retina and the image seen will be a blurred image. This is called myopia. The causes of refractive error: 1, the lens adjustment burden is too heavy, the lens becomes excessively convex and can not restore the original shape, or even the anterior and posterior diameter of the eye is too long. 2, disease: a considerable number of patients have suffered from measles, whooping cough and other infectious diseases, most of these sick children appear eye bulging, the refractive power of the eye decreased, vision is weakened. 3, noise: research by relevant experts shows that when the audio intensity is above 90 decibels, the sensitivity of the optic rod cells in the retina of the fundus to distinguish light brightness begins to decline, and the time to identify low light response is prolonged, accompanied by a weakening of color vision. 4, eat too much sweets: sweets are acidic food, on the one hand, a lot of consumption of calcium elements in the body, on the other hand, raise blood sugar, change the crystal osmotic pressure, is another cause of the formation of myopia bane, supervision of children eat less is good. The doctor’s tip: parents should do a good job to prevent children’s refractive error, when parents find that children often tilt their heads to look at things, watch TV or play computer always squint or have to walk very close to see things, if the above phenomenon, parents should promptly go to the hospital to check the child’s vision, to see if there is children’s refractive error, children’s refractive error need to do a good job of prevention, early detection for treatment.