Diabetic retinopathy, a long-term metabolic disorder caused by diabetes, causes lesions in the retinal blood vessels. When the small blood vessels of the retina are destroyed, hemorrhages and exudates from the small blood vessels leak out of the retina. As more and more small blood vessels are destroyed in the retina, more and more hemorrhages and exudates appear. The retina becomes swollen, and the vision becomes blurred. The lesion gradually spreads from the small blood vessels to the larger ones until all the blood vessels of the retina can be reached. A large number of small blood vessels eventually become completely occluded, interrupting the blood supply. This causes further damage to the already damaged retina, which is already deprived of blood and oxygen. As a natural compensatory response of human tissues, many new blood vessels grow on the anoxic retina or on the optic nerve papillae. However, these new blood vessels not only do not benefit the retina, but also pose a more serious threat and danger. Clinically, the presence or absence of neovascularization in the retina is classified as simple (also called non-proliferative) and proliferative diabetic retinopathy. Simple diabetic retinopathy mainly causes a mild to moderate loss of vision. The most common and predominant cause is hemorrhage, exudation, and edema in the macular region of the retina. The macula is the most important and sensitive part of the retina for vision in the human eye. It is rich in blood circulation. The macular edema is the most common phenomenon of diabetic retinopathy. In severe cases, edema and hemorrhage spread to most of the retina, and vision is severely impaired. When the lesion progresses to the proliferative stage it leads to severe vision loss or even complete blindness. Intraocular neovascularization is very fragile and can repeatedly rupture and bleed into the vitreous cavity, where vision is lost and only manual or light perception is seen. The hemorrhaged vitreous then proliferates and mechanizes, sticking to the retinal surface and contracting to pull the retina, leading to tractional retinal detachment. In addition, when large amounts of neovascularization also grow in the iris and atrial corners of the eye, it can cause an intractable increase in intraocular pressure, called neovascular glaucoma. These are all advanced manifestations of diabetic retinopathy, where the visual function has received maximum damage. Even after successful treatment, only a small amount of residual vision remains. If not treated, eventually even a little bright light will not be visible. Pure diabetic retinopathy needs laser treatment when it reaches a certain stage of development. If the time is longer, the retina will grow a lot of proliferating neovascular membrane, and even pull the retina detachment, then the effect of taking surgery will be worse.