Amblyopia is a common disease in pediatric ophthalmology and is defined as a condition in which the eye has no organic lesions and the corrected visual acuity does not reach 0.9. Parents of children who come to the clinic often do not have a clear understanding of the concept of “amblyopia”, either because they think that low vision means “weak vision”, or because they confuse “amblyopia” with refractive errors such as “myopia and hyperopia”. They either think that low vision means “weak vision”, which means “amblyopia”, or they confuse “amblyopia” with “myopia, farsightedness” and other refractive errors. In order to make the concept of “amblyopia” easier to understand, we can make a general analogy, although not quite appropriate, but it will help to understand. Let’s imagine the human eye as a camera. The main function of a camera is to make a clear image of the outside world on a negative, which can then be developed into a clear photo. The function of the human eye is similar to this, is also to make the external scene in the negative – is the retina clear image, and then through the optic nerve transmission into the brain visual center, so that we can clearly feel the world. If the camera’s negative image is not clear, generally the camera’s focus is not adjusted to the right, need to refocus. If the image on the retina of the human eye is not clear, it can also be that the eye’s focal length is not adjusted correctly, and also needs to be refocused. If no matter how hard the eye’s refractive system can not make the retina clear image, that is, the need to refocus is beyond the ability of the human eye, it will be diagnosed as “refractive error”, such as: myopia, hyperopia, astigmatism. At this point, external images must be imaged clearly on the retina with the involvement of lenses, i.e., glasses are required. With a clear negative, a clear photograph can be developed, but is a clear image on the retina necessarily “clearly perceived” by the visual center? The answer is no. A condition that does not allow for clear perception of a clear image on the retina is diagnosed as “amblyopia”. What kind of problem would this be? An example is a child with a congenital cataract. Cataracts block light from entering the eye, so the retina is not stimulated by light and the visual center is not stimulated by external objects, thus affecting the development of the visual system. If the cataract is not treated in time, when the child is older and undergoes cataract surgery, although the surgery is perfect and clear imaging is obtained on the retina, the perceptual ability of the visual center is not developed and a severe amblyopia will still form. Another example is a child with refractive parallax. One eye is the good eye and one eye is the eye with refractive problems. The ortho-optic eye always transmits clear signals to the visual center, while the affected eye always transmits blurred signals to the visual center. The blurred signal will bring interference to the perceptual system, and the visual center will prefer to accept the signal from the healthy eye and suppress the signal from the affected eye, over time, the affected eye will not develop, resulting in amblyopia. Although accurate refractive examinations were done later and appropriate glasses were worn, the vision of the affected eye could not be improved. Through the above 2 examples, we know that amblyopia is a problem that develops during the developmental period of the visual system, and of course, it is a problem that should be treated in time before the developmental period is over. This is what we mean by early detection and early treatment. Nowadays, children’s vision screening is carried out in many maternal and child health centers and health departments, providing conditions for early detection and treatment of amblyopia.