Posterior cataract is due to clouding of the posterior capsule after cataract surgery. The symptoms caused mainly include loss of vision, loss of clarity of vision or vision is no different from that before surgery, which is also invisible. The causes are mainly the following: 1. the patient has underlying diseases, such as diabetes, vitreous opacity, iritis, etc. 2. childhood-type cataracts, which have a particularly high incidence of post-operative cataracts. At present, the main treatment is postoperative laser resection of the posterior capsule, which is more effective, but many patients may experience discomfort after the resection. Especially for pediatric cataracts or cataracts with congenital diseases, posterior capsulotomy or tearing of the posterior capsule is done during the surgery, which will prevent the occurrence of posterior cataracts.