In general, cataract surgery does not require a second surgery. The special cases that require a second surgery are as follows: 1. The posterior capsule membrane of the lens ruptures during the surgery for some reasons, and after a long time, the IOL will become deviated or fall out into the vitreous cavity because there is no intact posterior capsule membrane to support it. In this case, it is necessary to surgically remove the deviated IOL, remove the overflowing vitreous body, make IOL repositioning, or fix the IOL to the normal position with sutures if necessary. 2. Various reasons cause endophthalmitis after cataract surgery, the consequences of endophthalmitis are very serious and will be devastating to the eye, which may eventually cause eye removal surgery. So once endophthalmitis occurs one must receive intraocular injection of antibiotics in the first place and do a combined vitrectomy; 3. For patients with congenital cataract, cataract ultrasound emulsion aspiration and combined IOL implantation have been done at a young age and IOLs are also put in. However, as the eye develops, the degree of the originally implanted IOL is no longer appropriate for the child, and it may be necessary to do an IOL replacement surgery after adulthood. The above three special cases are not common in clinical practice, so generally cataract surgery only needs to be done once and there is no need for a second surgery.