Cataract surgery usually requires the implantation of an IOL, and in some cases it requires a second-stage implantation or no implantation of an IOL. Generally cataract surgery refers to cataract extraction combined with IOL implantation, where the IOL is put in after the cataract is removed, which is done in a single operation, and if there are no other conditions, IOL implantation is usually required. There are also some special cases where only cataract removal without lens implantation is done, such as those with fundus lesions or other diseases of the eye that are not suitable for lens implantation, those with high myopia, or congenital cataract surgery for younger children, usually waiting for the eye axis to reach the standard before implanting an IOL in the second stage. The IOL implanted during surgery can be used for a long time if there are no special circumstances. If the IOL position is abnormal or traumatized, replacement should be considered. Whether cataract surgery requires the implantation of an IOL should be decided by a specialized doctor based on the results of the examination.