The best corrected visual acuity is usually around 1.0 or 1.2. If it is lower than 0.8, the eye may have some organic problems or amblyopia. If the best corrected visual acuity is less than 0.8 in children, the possibility of amblyopia is higher and the cause of amblyopia needs to be found, which may be caused by high farsightedness or myopia. In this case, not only glasses, but also some masking treatment and visual function training may be required. If amblyopia is ruled out in adults and the corrected visual acuity is still below 0.8, there may be some organic pathology, such as cataract or fundus pathology, and detailed examination is needed to determine this. If cataract is the cause, cataract surgery is needed. If it is caused by a lesion of the fundus, it is necessary to take an injection or surgery to correct it according to the type of lesion.