There are many causes of amblyopia, the most common ones are: 1. Refractive error Most often occurs in children with high refractive error (myopia, hyperopia, astigmatism) who are not wearing corrective glasses, mostly in both eyes. Experience light with appropriate glasses, vision will gradually improve or restore, the younger the age of starting to wear glasses, the better the treatment effect. 2. Strabismus Children with strabismus often suffer from visual disturbances (such as seeing one thing in both eyes as two things: diplopia) and discomfort. In order to eliminate this discomfort, the visual center of the brain actively inhibits the visual impulses transmitted by the strabismus, and amblyopia is formed. Children with strabismus also have refractive error, so it is important to correct the refractive error as early as possible, as well as to cover the strabismic eye appropriately and correct the strabismus with surgery when appropriate. Formal deprivation When eye diseases affecting vision (such as congenital cataract, ptosis, corneal leukoplakia, etc.) occur in infancy before the visual function has developed, they affect the full entry of light into the eye and deprive the retina of its role in receiving normal light stimulation, resulting in functional impairment and amblyopia. In the case of form deprivation amblyopia, the cause of the deprivation should be removed as soon as possible, for example, congenital cataracts should be operated as soon as they are detected, and any surgery later than 3 months will leave a certain degree of amblyopia. Refractive aberration Refractive aberration means that the difference between the two eyes is large, such as a normal eye and a highly hyperopic eye. As the size and clarity of the object image formed by the retina of both eyes are different, the image cannot be well integrated. The visual center of the brain can only suppress the object image of the eye with greater refractive error, and amblyopia is produced. In this case, it is also necessary to wear glasses as early as possible to correct the refractive error and cover the eye with better vision for treatment.