When you walk into a pediatric ophthalmology clinic, many people wonder how so many children can be seen. There is nothing unusual about the appearance of their eyes, but many of them come to the clinic because of amblyopia. Amblyopia is an eye disease that seriously endangers the visual function of children, it does not get better with age, on the contrary, if it is treated after the age of 12, it will be difficult to cure, and if it enters adulthood, treatment is basically hopeless. Therefore, the early detection and treatment of amblyopia in children is especially important, so today we will tell parents: what is amblyopia? How can parents detect amblyopia in their children at an early stage? What is the normal visual acuity of a child? Before explaining amblyopia, let’s first explain what the normal visual acuity of children of different ages should be. Under normal circumstances, a child’s visual acuity gradually tends to normalize with age. A child’s visual acuity is about 0.2 at the age of one, 0.4 at the age of two, 0.6 at the age of three, 0.8 at the age of four, and 1.0 at the age of five. Is low visual acuity amblyopia? After knowing the vision of a normal child, is it considered amblyopia if the vision is lower than normal? This is not the case. Amblyopia is strictly defined, and low vision is not considered amblyopia. First of all, if the corrected visual acuity is lower than 0.9 after dilated eye examination, it is possible that the child is amblyopic. Of course, a visual acuity of less than 0.9 is considered amblyopic for children 5 years old and older, while children 4 years old have a corrected visual acuity of less than 0.8 and children 3 years old and younger have a corrected visual acuity of less than 0.6. In addition, in the case of low corrected visual acuity, organic eye pathologies, such as congenital abnormalities of the eye, fundus and intracranial diseases, should be ruled out, and poor vision in children should not be easily considered as amblyopia. After the diagnosis of amblyopia is confirmed, the cause of amblyopia must be found. There are several types of amblyopia: strabismic amblyopia, refractive error amblyopia, refractive error amblyopia and form deprivation amblyopia. Amblyopia classification tips: strabismic amblyopia: the child has strabismus, one eye is constantly in a skewed position, the visual cortical center of the brain will inhibit the visual function of the strabismic eye, and long-term amblyopia will appear in this eye. Refractive amblyopia: refractive error refers to the difference in refractive error between the two eyes of the child, resulting in different clarity or size of objects projected to the fundus of the two eyes, the two objects cannot be fused together, the brain will inhibit the refractive error of the larger eye, and over time the eye will easily form amblyopia. Refractive amblyopia: Children with high refractive error, especially high hyperopia or astigmatism, are prone to this type of amblyopia. Most of them are not corrected by glasses, but with proper glasses, the vision can be improved gradually. Morphological deprivation amblyopia: typically occurs in children with corneal clouding, ptosis, congenital cataracts, or long-term improper coverage of one eye. These problems cause light to not enter the eye sufficiently and the macula at the base of the eye cannot receive normal light stimulation, and a clear image of the object cannot be formed. When the macula does not function for a long time, its function gradually deteriorates and amblyopia occurs. These children often have a combination of strabismus or nystagmus.