In the early stage of the lesion, the patient may not feel anything, but examination of the fundus may reveal changes in the retina such as microangiomas, hemorrhages, and exudates, indicating that diabetes has existed for a certain period of time and requires good control of blood sugar, blood pressure, and lipids to prevent or slow down the aggravation of the lesion. This is also the best time for prevention. Therefore, diabetic patients should go to the hospital for regular checkups even if they do not have eye discomfort. Diabetic macular edema can occur at any period of diabetic retinopathy. Even if the retinopathy outside the macular area is not severe, once macular edema occurs, the patient’s central vision will be affected, which is manifested as blurred vision and distortion of vision (straight line becomes curved, and seeing things becomes bigger or smaller). When the retinal neovascularization hemorrhages and enters the vitreous cavity, the patient may feel a dark shadow floating in front of his eyes. Do not think that this is a general “flying mosquitoes”, it is a diabetic retinopathy into the proliferative stage of the performance, is the need for timely retinal laser photocoagulation treatment indications. Therefore, once the diabetic patients appear the so-called “flying mosquitoes”, must go to the hospital to check, so as not to miss the time of treatment. If the vitreous hemorrhage is more, not only the black shadows in front of the eyes significantly increased, thick, vision will also be significantly reduced, or even completely blind. In some patients, vitreous hemorrhage can be partially absorbed after a certain period of recovery, and the patient’s vision can be partially improved, but if retinal laser photocoagulation is not performed or the condition does not allow laser treatment, or if laser treatment is not sufficient, vitreous hemorrhage will occur again. Repeated vitreous hemorrhages eventually lead to vasoproliferative vitreoretinopathy, retinal detachment or retinal detachment of retinal origin with retraction, and the patient is often blind. If neovascularization occurs in the iris or atrial angle, neovascular glaucoma develops and patients experience uncontrollable eye pain with headache, nausea, and vomiting because the IOP is often higher than 50-60 mmHg. Sometimes the IOP is gradually increased and the patient tolerates the high IOP without severe eye pain, but often has head congestion. When the lesion progresses to this stage, vision is mostly poor, often with no light perception.