Cataract is a common eye disease that causes vision loss or even blindness due to clouding of the lens, especially in the elderly. Surgery is the only way to improve vision and restore sight. The majority of patients with cataracts can obtain satisfactory vision after surgery, but some postoperative patients have unsatisfactory vision for the following reasons: a. Concurrent fundus lesions: Many elderly people suffer from macular degeneration, optic nerve atrophy and other fundus lesions. If accompanied by diabetes, there may be diabetic retinopathy, these people if the preoperative lens clouding degree is serious, fundus examination may not see the lesion, even using 0CT is difficult to detect, such patients, postoperative vision may be difficult to achieve the ideal vision. If the patient is highly myopic and has retinopathy before surgery, it is difficult for him to achieve normal vision after cataract surgery. Secondly, intraoperative accidents: it is difficult for any skilled surgeon to guarantee that no accidents will occur during surgery. Such as intraoperative bleeding, rupture of the posterior lens capsule, vitreous detachment, etc., if not handled properly, can affect vision after surgery. Third, postoperative complications: early complications after surgery, such as inflammation, secondary glaucoma, IOL deviation, entrapment, macular edema in the fundus, can affect vision. The postoperative vision is hardly satisfactory. Refractive error: The cause of this can be pre-operative, astigmatism due to the surgical incision, or IOL calculation deviation, all of which can affect visual acuity. V. Posterior cataract: the clouding of the posterior lens capsule can affect vision. VI. Other late complications: such as retinal detachment, fundus bleeding in the elderly due to arteriosclerosis, hypertension, etc., can affect vision. In case of poor vision after cataract surgery, the cause should be identified and the treatment should be targeted. As a doctor, we should do all kinds of preoperative examinations as thoroughly as possible to make postoperative measurements, do each operation carefully to reduce errors, and tell patients and their families about the common complications that may occur so that they can have a good idea. As a patient, if you choose a doctor you trust to operate, you should believe that any doctor wants to do every patient well, and will never be negligent, and the trust and understanding between doctors and patients is the basis for resolving misunderstandings.