Diabetes mellitus is a metabolic disorder caused by defective insulin secretion or insulin dysfunction, which can eventually lead to damage and dysfunction of multiple systems, including the brain, eyes, kidneys and peripheral nerves. Diabetic retinopathy (DR) is the most important manifestation of diabetic microangiopathy and is a kind of fundus lesion with specific changes, which is one of the serious complications of diabetes and one of the major blinding eye diseases. Diabetic retinopathy without retinal neovascularization is referred to as non-proliferative diabetic retinopathy (NPDR) (or simple or background), while diabetic retinopathy with retinal neovascularization is referred to as proliferative diabetic retinopathy (PDR), based on the presence or absence of retinal neovascularization. The main lesions of diabetic retinopathy manifest as microaneurysms, hemorrhages, hard exudates, absorbent cotton spots, venous beading, intraretinal microvascular abnormalities (IRMA), macular edema, and optic neuropathy. Extensive ischemia leads to neovascularization, preretinal hemorrhage, vitreous hemorrhage, and retinal detachment by traction. In proliferative diabetic retinopathy, retinal ischemic and hypoxic damage stimulates neovascular growth. Neovascular growth can be detrimental to the retina, causing fibroplasia and sometimes retinal detachment. Neovascularization can also grow into the vitreous or cause vitreous hemorrhage. Compared to non-proliferative diabetic retinopathy, proliferative diabetic retinopathy is more dangerous to vision and can lead to severe vision loss or even complete blindness. Ye Nan Wang, Ophthalmology Department, Xuanwu Hospital, Capital Medical University “Prevention is better than cure”: Proper control of diabetes is the first step in the prevention and treatment of diabetic retinopathy. The main role of treatment is to slow or even stop the progression of the disease, but not to reverse it to before it started, so it is best to visit your ophthalmologist at least once a year for an examination. Tests such as fundus fluorescence angiography are required if necessary. Fundus fluorescence angiography can detect abnormal fluorescence when diabetic retinopathy has not been detected by fundoscopy. Microangiomas are found much earlier and more often on fundus fluorescence angiography than what is seen on fundoscopy. Others, such as capillary dilation, increased permeability, areas of no perfusion, arteriovenous abnormalities, exudation and hemorrhage, and neovascularization, have specific manifestations on fundus fluorescence angiography. In response to the manifestations of fluorescence angiography, an individual treatment plan is developed to suit each patient’s condition, such as medication, laser treatment, surgery, etc. When an ophthalmologist treats diabetic retinopathy with laser photocoagulation, patients usually experience only mild eye discomfort, such as eye pain or red eyes, which can be relieved with medication. Once the diabetic retinopathy is severe enough that a large amount of blood flows into the vitreous and is difficult to absorb, vitreoretinal surgery may be required.