Cataracts are usually not visible in a mirror. Cataracts are not a disease of the surface of the eye and cannot usually be diagnosed using visual observation. Diagnosis of cataracts usually requires a slit lamp, corrected visual acuity, intraocular pressure, and funduscopic examination, supplemented by dilated pupil examination for specific types of cataracts. A cataract is diagnosed if the patient’s lens appears cloudy on examination and the corrected visual acuity is less than 0.7. The cause of cataract may be related to age, metabolic diseases, ultraviolet radiation, etc. The main manifestations are progressive vision loss, myopia or astigmatism, monocular diplopia or hyperopia, etc. The treatment of cataract is mainly surgical. Cataract treatment is mainly surgical, usually by removing the cloudy lens and then implanting an IOL. People over the age of 50, those with a family history of cataracts and high-risk groups such as welders are advised to have an eye examination once or twice a year to detect the condition in time.