Photodynamic therapy (PDT) was first used in the treatment of malignant tumors, and was applied to the clinical closure of choroidal neovascular membrane (CNV) at the end of last century, which is based on the principle of first injecting photosensitizing drugs into the body through a vein, due to the selective accumulation of photosensitizing drugs at the site of neovascularization, so when a certain wavelength of cold laser irradiation, the photosensitizing drugs can be activated The photochemical reaction occurs, releasing energy locally and generating a large number of free radicals, thus oxidizing damage and closing the neovascularization. The advantages of PDT are that the photosensitizer accumulates less in the normal blood vessels, the normal retina and choroid are not affected, the laser that excites the photosensitizer does not produce heat and does not damage the adjacent retinal tissue, and the central vision is preserved to some extent, overcoming the disadvantages of photocoagulation therapy in this regard. The disadvantages of PDT are that it does not improve visual acuity, it does not alter the pathological basis of CNV and metabolic abnormalities, thus it does not stop the disease progression, and it is expensive to treat. In addition, some studies have shown that PDT can seal CNV for a short period of time, but after a period of time it relapses and new leaks appear, requiring repeated treatment.