A Prospective,randomized controlled study of eyes with dense nucleus were enrolled. Patients were assigned to two groups: Group I: the participants had a intraocular lens implantation, while in Group II, the participants had a traditional cataract surgery. Investigators give two groups a secondary intraocular lens implantation. Investigators compare the visual acuity, incidence of high intraocular pressure, incidence of visual axis opacification, uveitis and iris/pupil abnormality between two groups after the first and the second surgery, aiming at comparison of minimal invasive lens surgery and traditional cataract surgery for treating congenital cataracts