Amblyopia: visual development caused by monocular strabismus, uncorrected refractive error and high refractive error, and form deprivation, where the best corrected visual acuity in one or both eyes is lower than the corresponding age-specific visual acuity, or where the visual acuity in both eyes differs by two or more lines. The lower limit of age-specific reference values: 0.5 for 3-5 years old, 0.7 for 6 years old and above. Amblyopia classification: Strabismic amblyopia: amblyopia caused by monocular strabismus Refractive amblyopia: 1.5 DS difference between the two eyes and 1.0 DC difference between the two eyes, which can cause amblyopia to form in one eye with a higher refractive error. Refractive amblyopia: mostly occurs in patients with high refractive error who have not worn refractive correction glasses. It is mainly seen in patients with high hyperopia or astigmatism in both eyes, and the best corrected visual acuity is equal or similar in both eyes. It is generally accepted that hyperopia ≥ 5.00 DS and astigmatism ≥ 1.0 DC increase the risk of amblyopia. Formal deprivation amblyopia: caused by deprivation factors such as refractive interstitial clouding and ptosis, amblyopia can be unilateral or bilateral, with unilateral being more severe than bilateral. Suggestions for vision screening methods: Different visual acuity scales are used for different ages, and graphic visual acuity scales are recommended for ages 3-5. For those younger than 3 years old, PL, OKN, VEP, and single letter vision charts can be used, with emphasis on qualitative examination of the difference in visual acuity between the two eyes.