Photodynamic therapy is a laser technique for the treatment of choroidal neovascularization in the subcentral macular sulcus. It involves injecting the photosensitizer Vizodar into the body, and when it circulates to the eye and binds choroidal neovascularization in large quantities, then a long wavelength cold laser is used to irradiate the lesion to selectively destroy the abnormal neovascularization and finally close the neovascularization. It has almost no damage to normal tissues, thus avoiding the damage to normal tissues of the fundus while treating CNV with conventional thermal laser. It is the only internationally recognized laser therapy that effectively acts on the lesions in the central macular recess, which has maintained useful vision and improved the quality of life for many patients in the clinic. When it comes to photodynamic therapy, we should mention a disease —- exudative age-related macular degeneration, which is an important age-related blindness eye disease. The cause of age-related macular degeneration is not very clear, but is generally thought to be related to age, smoking, chronic light damage and other factors. Patients often do not have any symptoms in the early stage, and it has little effect on visual acuity. A few patients have blurred vision, distorted vision and difficulty in reading. When there is a large amount of hemorrhage in the macular area of the fundus, the central vision can be drastically reduced. It obviously affects the quality of life. These symptoms are mainly caused by pathological changes in the “macula” of the retina, which is responsible for vision and central visual field, and the incidence increases with age. For the treatment of exudative age-related macular degeneration, if the location of the neovascular membrane is far from the central recess, the neovascularization can be closed by ordinary laser photocoagulation to prevent the development and expansion of the lesion. If the choroidal neovascularization is located under the central macular recess, the treatment is more tricky and photodynamic therapy should be taken.