Before 1980, the only way to treat cataract abroad was to open the posterior capsule by surgery, which required general anesthesia. In China, the "needle extraction" operation is adopted, which is a kind of operation to push the cataract capsule under the vitreous body and enjoys a high reputation internationally. Later, researchers from Paris University and Berne University in Sweden found that laser-induced shock waves were extremely useful for removing secondary cataracts.