Amblyopia is a disease in which the best visual acuity in one or both eyes is lower than normal, but no organic changes in the eye corresponding to that reduced visual acuity are found. The incidence of this disease in China is 2% to 4%. Clinically, amblyopia is often characterized by lower than normal best corrected visual acuity, strabismus, refractive error, and lack of stereo vision. What is the key to preventing and treating amblyopia? First, it is important to clarify a concept – the critical period of visual development. It is generally believed that the visual system matures around the age of 3. The development of vision between the ages of 3 and 8 still has a certain degree of plasticity and may even be prolonged to some extent. Therefore, prevention and treatment of amblyopia should start with children, early detection, early treatment, most amblyopic children’s vision can still be restored to normal. Since young children are naturally naughty and do not concentrate easily, it makes it difficult to assess the vision accurately. Here we introduce several testing methods for parents. Color ball test method: If the child is too young to check the visual acuity chart, you can use a colored ball to shake in front of the eyes to see if the child’s eyes move with the ball movement and if the amplitude of the two eye movements are the same; if one eye is attracted and the other looks elsewhere or the amplitude of the two eye movements are not the same, it is necessary to consult a doctor to see if there is a strabismus or refractive error that causes imbalance in the vision of the two eyes. Monocular masking method: You can alternately cover the child’s eyes and see how the child reacts. If the child’s left eye is covered, the child does not react and plays as usual; while when the right eye is covered, there is obvious resistance, crying or grabbing the cover with hands, etc., it indicates that the right eye has better vision than the dominant eye and the left eye may have amblyopia. Visual acuity chart method: A young child should be taught to read the visual acuity chart by the age of about 3. You can take advantage of the children’s nature of being willing to be praised and give more encouragement and praise during the process of vision check to make them cooperate with the vision check. For children suspected of having amblyopia, a comprehensive eye examination should be conducted to exclude organic pathologies such as congenital cataract, vitreous hemorrhage, retinopathy of prematurity, as well as mild optic nerve hypoplasia, mild optic nerve atrophy and minor macular abnormalities that are most easily overlooked. A special point to emphasize here is that the key to vision development is visual stimulation. The development of visual pathways within the central nervous system requires the brain to receive equally clear, focused images from both eyes. Any lesion that seriously interferes with the development of the visual pathway in the brain can lead to amblyopia. For example, long-term edema of a child’s eyelid from a mosquito bite that cannot be opened, or long-term gauze coverage of the affected eye after intraocular surgery for an eye trauma may cause amblyopia in that eye. For children with congenital cataracts or severe congenital ptosis, amblyopia should never be treated after surgery. There are many ways to treat amblyopia, but the overall goal is one: to give the patient the best possible vision. The first and most important step in treatment is to make a clear image projection onto the central macular recess. In children with deprivation amblyopia, the exact cause is sought and removed. For refractive amblyopia, the child must wear glasses to correct the apparent refractive error. On this basis, the child is encouraged to use the amblyopic eye, which can be treated with masking therapy and suppression therapy. There are many factors that affect the efficacy of treatment, summarized as follows: Age of treatment: the earlier the age of treatment, the greater the possibility of recovery of vision, most of the results are better when treatment starts before school age, and the results are worse after the age of 10. The severity of amblyopia: according to the best corrected visual acuity of the child can be divided into three cases: the best corrected visual acuity of 0.6 to 0.8 is mild amblyopia; 0.2 to 0.5 is moderate amblyopia; less than or equal to 0.1 is severe amblyopia. Among them, mild amblyopia has good efficacy, followed by moderate amblyopia, and severe amblyopia is the worst. Parents’ cooperation and children’s compliance: First of all, parents should understand the treatment method used by the doctor, actively cooperate, and encourage their children more to increase their compliance. If the parents do not understand or the child often removes or uncovers the eye patch to peer through the lens during the masking therapy, these practices can lead to a decrease in the effectiveness of the masking therapy or even its complete ineffectiveness.