Definition of amblyopia: Amblyopia is a condition in which the best corrected visual acuity in one or both eyes is lower than the corresponding age due to monocular strabismus, uncorrected refractive error, high refractive error, and form deprivation during visual development; or amblyopia is a condition in which the visual acuity of both eyes differs by 2 lines or more and the visual acuity of the lower eye is amblyopic. The lower limit of the normal value of visual acuity for children of different ages: the lower limit of the normal value of visual acuity for children aged 3-5 years is 0.5, and the lower limit of the normal value of visual acuity for children aged 6 years and above is 0.7. Here is a little explanation: “Visual development”: children should not be too nervous if amblyopia occurs during the visual development period, because the cerebral cortex is very plastic at this time. Timely treatment will give good results. The golden treatment period is generally before the age of about 9 years old, teenagers will be less effective, and the effect of adult amblyopia treatment is basically unsatisfactory. ”Best corrected visual acuity”: the visual acuity used to diagnose amblyopia is the best corrected visual acuity, not the bare eye visual acuity. ”Age-appropriate visual acuity”: 0.5 before the age of 5 and 0.7 after the age of 5. In clinical work, two types of errors should be avoided: (1) when diagnosing amblyopia in children, a systematic examination must first be performed to exclude organic changes in the eye; at the same time, the relevant factors leading to amblyopia should be identified, and amblyopia should not be diagnosed on the basis of only one indicator of visual acuity; (2) according to the developmental rules of children’s visual acuity, the diagnosis of amblyopia should be made on the basis of the developmental rules of children’s vision. (2) According to the rules of children’s visual development, the diagnosis of amblyopia in children aged 3-7 years should not be based on visual acuity below 0.9, but should refer to the lower limit of the normal value of visual acuity at the corresponding age.