IOL implantation is a commonly used method of lens-free eye correction in the last 30 years. In other words, after removing the cataract, an artificial lens is implanted in the eye to replace the original lens and reconstitute an approximately normal refractive system, which is more in line with the anatomical and physiological requirements of the eye. The magnification of the artificial lens is only 0.2%-2%, and the artificial lens is close to the center of rotation in the eye, which is relatively stable and does not produce the trigeminal effect. After implantation, the optical imaging quality is higher and does not produce adverse reactions such as image inequality, visual field reduction, cycloplegia and vertigo. The patient needs to undergo a thorough eye examination before surgery, such as slit lamp, intraocular pressure, tear duct, corneal endothelium, etc. He also needs to do the measurement of the IOL degree through relevant instruments: eye axis, corneal curvature, anterior chamber depth, etc. These parameters are calculated through a formula to derive the theoretical degree of the IOL implanted in the patient’s eye, and the doctor adjusts it according to the patient’s life requirements (orthokeratology or myopia) to decide the specific degree of implantation. The method of IOL implantation should be determined by the specific conditions of the eye and the surgeon’s own technical characteristics. The main methods include: ① Intracapsular implantation: usually after the lens is removed, the lens capsule is left behind and the IOL is implanted within it; ② Ciliary sulcus implantation: when the capsule is incomplete, such as in the case of trauma, or in the case of second-stage IOL implantation, the IOL is mostly implanted in the ciliary sulcus. This method requires a peripheral capsular membrane as well as an intact suspensory ligament for support. When the capsule is not sufficient to support the IOL, a transscleral suture posterior chamber type IOL can be taken accordingly; ③Other: when the patient has sufficient corneal endothelium and anterior chamber depth, iris-clamp anterior chamber type IOL implantation can be considered. The choice of IOL should be decided according to the patient’s specific situation. IOL materials are generally divided into non-folding IOLs and folding IOLs. The non-folded IOL, also called hard lens, is implanted through a 5.5-6 mm incision, mostly made of PMMA material, and is completed with the small incision surgery often used today. The foldable IOL, also called soft lens, only needs to be implanted through an incision of 3.0mm or less, and is mostly made of acrylate material, whose biocompatibility is the same or even better than PMMA material, and its foldable design is easy to implant through a small incision, which has the advantages of small postoperative astigmatism, fast vision recovery, and less surgical complications. Foldable material lenses are soft, and if ciliary sulcus fixation is performed, a three-piece acrylic IOL with loops of PMMA material is recommended, which is more conducive to stability in the ciliary sulcus. In case of patients with uveitis, heparin-treated IOLs are recommended to alleviate postoperative intraocular inflammation and reduce postoperative IOL surface cell deposition. The choice of an IOL also requires consideration of its function. The principle is to reduce the influence of peripheral light on the central light (reduce spherical aberration) by improving the shape of the IOL surface, which makes the imaging clearer, especially when the dark pupil is large, similar to the current flat TV, which can improve the postoperative patient’s contrast It can improve the contrast sensitivity of postoperative patients and achieve the effect of “high definition”. Patients with high astigmatism often need to wear several pairs of glasses to solve the problem of seeing objects at different distances. These patients can be implanted with an artificial lens to correct astigmatism and solve the problem of cataract and astigmatism at the same time, thus killing two birds with one stone. The natural lens has adjusting power, and as the adjusting power decreases after the age of 45, the phenomenon of presbyopia occurs. For patients who do not want to wear a lens, they can consider implanting an adjustable or multifocal lens to restore their youthful eyes. However, not all patients are suitable for these high-end IOLs and the decision needs to be based on their eye characteristics. In summary, modern IOLs have evolved to provide a variety of options for cataract patients. A comprehensive clinical analysis should be conducted by weighing the patient’s age, financial situation, eye conditions and the patient’s needs in order to select the most appropriate correction method for each patient for individualized treatment in order to achieve truly ideal results.