A cataract is a clouding of the lens. Symptoms: Gradual loss of vision. Blurred vision, no eye pain or redness. Treatment: Surgery is the mainstay; medications are not effective. The surgical options are cataract ultrasound emulsification combined with folding IOL implantation and small incision cataract extracapsular extraction combined with IOL implantation. The most advanced method is the former, which takes only about 10 minutes to perform, with a 3mm incision, minimal surgical response and rapid vision recovery. No hospitalization or only 3 days of hospitalization is required. Post-operative astigmatism is small. IOL: There are more varieties, according to materials, PMMA, silicone, hydrophilic and hydrophobic polyacrylate. Spherical, aspheric, modulating, and blue light filtering IOLs by function. By shape: Folded, non-folded. Surgery is no longer limited to cataracts with cloudy lens only, but also includes refractive surgery for clear lens, myopic-farsighted and astigmatic eyes, which are corrected by cataract ultrasonic emulsion IOL implantation.