Parents often ask, “Why is our child amblyopic when we both have good eyes? The following is an introduction to several factors that affect the visual development of infants and children causing amblyopia. One, moderate to high refractive error: refractive error is the collective name for farsightedness, myopia and astigmatism. When the refractive error is too high, without timely prescription lenses, the imaging in the fundus is blurred, the visual development is not fine enough, it will form refractive amblyopia. It is generally believed that hyperopia greater than 300 degrees, 600 degrees of myopia or 200 degrees of astigmatism, more likely to cause refractive amblyopia, this type of amblyopia is more common, the right method and adhere to the training is not a big problem! Refractive aberration: When the difference between the degrees of both eyes is 150 degrees or astigmatism is 100 degrees, it is pathological refractive aberration. Refractive parallax amblyopia is mainly manifested in the vision of one eye is much better than the other, but because there is no comparison of binocular vision, and no other too obvious symptoms, so it is easy to be ignored, and thus miss the best time for treatment, but if found in time, the training effect is still relatively ideal, kindergarten vision screening is particularly important! Third, strabismus: strabismus refers to the inability of both eyes to simultaneously look at a unified target, ostensibly meaning that one can look at the bowl and the other at the pot, however, this is not a good thing. After the appearance of strabismus, because the direction of gaze of both eyes is not the same, can not be integrated, the brain will selectively inhibit the strabismus eye, strabismus eye can not get visual stimulation will form amblyopia. Internal strabismus is the most likely cause of amblyopia, four times more likely than external strabismus, and external strabismus and amblyopia are not necessarily a direct cause and effect relationship! The difficulty of strabismic amblyopia training depends mainly on whether the retinal correspondence is normal! Four, form deprivation: the human eye is like a camera, the lens and light path must be pure and transparent, once the lens or light path problems, you can not take a clear image, in ophthalmology is called form deprivation. The more common ones are congenital cataracts, ptosis, etc. Formal deprivation amblyopia is a more difficult amblyopia to treat, and the timing of surgery and training is very important! V. Congenital diseases: Amblyopia caused by diseases such as nystagmus and total color blindness are generally more difficult to treat! The effect of training is also limited!