For the first 20 years, refractive surgery was synonymous with corneal surgery to compensate for refractive error by changing the anterior surface morphology of the eye. IOLs for crystalline eyes (IOLs) represent a new type of IOL that expands the scope of corneal refractive surgery and provides a new method of visual correction for surgeons and patients. For IOL implantation in crystalline eyes, we currently perform ICL implantation surgery. In the preoperative indication assessment, we need to focus on refraction, anterior chamber depth, etc. For the current ICL lens, the degree of myopia correction is in the range of -3D – 20D, anterior chamber depth needs to be greater than 2.8mm, and corneal endothelial cell count also has an approximate requirement according to age, with corneal endothelial cell count at age 20 It is better to exceed 2500/mm2 at age 20 and not less than 2000/mm2 at age 40. Considering the incidence of cataracts, it is better to be no older than 50 years old. In addition, there are other indications. For children with high myopia in one eye, ICL surgery is more advantageous than keratoconus surgery because it allows the lens to be removed and replaced. Most of the patients commonly encountered in outpatient clinics for ICL surgery are some of the patients who are not suitable for keratoconus surgery, including high myopia and high astigmatism. High myopia and high astigmatism somehow mean poor visual quality after keratoconus surgery, decreased predictability of surgery, and increased incidence of corneal folds, so ICL has its advantages over keratoconus surgery. In addition, commonly encountered are those who are not candidates for keratoconus surgery due to abnormal corneal topography, such as those with a potential risk of corneal dilatation, suspected cone corneas or treated stable cone corneas, and those for whom full correction of keratoconus surgery is predicted to compromise visual quality due to high (>50D) or low (<34D) postoperative corneal curvature due to excessive refractive error, ICL ICL has been shown to be superior for this group as well. Of course, there are few people who are not suitable for excimer laser keratomileusis due to thin corneas. ICL has specific contraindications, including uveitis, corneal endothelial lesions, low endothelial cell count, glaucoma, cataract, pigment spreading syndrome, and crystalline capsular detachment. However, there is a patient with corrected visual acuity of 0.2 and naked eye visual acuity of 0.04. After repeatedly comparing the feeling of wearing glasses and not wearing glasses, he still decided to have the surgery, and after the surgery, he reached 0.3 and removed his glasses, and he was very satisfied.