There are three main purposes of cataract surgery: i. To increase visual acuity Cataract patients have reduced the transparency of the lens due to lens clouding and caused visual impairment. When this visual impairment gradually worsens and affects the patient’s work, study and life, surgery can be performed. In other words, when cataract surgery is performed depends largely on the cataract patient’s need for vision. Since the need for vision varies from person to person, there is no definite standard as to what degree of visual impairment can be operated. Generally speaking, state cadres, intellectuals, drivers and others with high vision needs can consider surgery relatively early. General workers, farmers, housewives, etc. do not have a very urgent need for vision and can consider surgery relatively late. On the other hand, when to perform cataract surgery also takes into account the surgeon’s own technical conditions and the equipment and other related facilities that the hospital has. If the surgeon has been in the field for a long time and is very experienced in surgery and the hospital has first-class surgical equipment and instruments, then the timing of surgery can be appropriately advanced. Otherwise, delay the surgery as much as possible. According to WHO standards, a corrected visual acuity <0.3 is identified as a low vision eye. Therefore, most surgeons choose to perform cataract surgery when the corrected visual acuity is below 0.3. In individual cases where the patient is in urgent need and the surgeon is technically confident, surgery can also be performed if the visual acuity is 0.3 or 0.4. Second, treatment of other eye diseases First, when other eye pathologies are caused by cataracts, cataract surgery needs to be selected. For example, if the cloudy lens, due to the change of osmotic pressure, more water accumulates in the lens in a short period of time, making it swell sharply, the lens volume becomes larger, pushing the iris forward, the anterior chamber becomes shallow, the atrial angle becomes narrower, and at the same time intensifies the physiological pupillary block, thus causing the IOP to rise and inducing acute angle-closure glaucoma; or because of the overripe cataract, the lens cortex that exists in the atrial water for a long time deposits in the anterior chamber angle or is In addition, patients with cataracts who also have a combination of cataracts and atrial water may have poor drainage of atrial water, causing secondary glaucoma (lens dissolving glaucoma). Secondly, cataract patients with other eye diseases that affect the treatment of eye diseases need cataract surgery first. If a patient has both cataract and diabetic retinopathy, cataract surgery is often required for the treatment of the latter. In addition, when cataracts are caused by eye diseases and the formation of cataracts affects the treatment of eye diseases, cataract surgery is needed first. For example, cataracts caused by retinal detachment often require cataract surgery first and retinal detachment surgery later. Third, for cosmetic purposes, the pupil area of mature or over mature cataract patients gradually turns white, which seriously affects the appearance of patients. Some patients in this category have completely lost their vision in the affected eye and cataract surgery cannot restore their vision. However, for cosmetic purposes, they often want to have cataract surgery.