Hyperglycemia: a key factor in the control of diabetic retinopathy Hyperglycemia is a key reversible risk factor for the development of DR. The pathological changes caused by a persistent hyperglycemic state are not only retinopathy, but invade all parts of the eye, including conjunctival lesions, diminished corneal perception, cataracts, anterior uveitis, neovascular glaucoma, refractive and regulatory changes, and ocular muscle paralysis. The duration of diabetes is the most important risk factor for DR, and patients with longer duration of diabetes almost always have varying degrees of retinal vascular disease. In addition, hypertension, dyslipidemia, obesity, nephritis, peripheral neuropathy, poor lifestyle (including smoking and alcohol consumption), and ocular factors such as myopia and posterior vitreous detachment (PVD) are all risk factors associated with DR. Targeted screening of these risk factors and timely treatment measures are essential to control the progression of DR from the non-proliferative to the proliferative phase. In addition, it is worth mentioning that DR may not have conscious symptoms in the early stage of the disease, and the patient’s visual acuity is not a criterion to determine the presence of DR. In order to miss the best time for treatment as much as possible, the fundus should be checked as soon as diabetes is diagnosed, and it should be reviewed regularly once or twice a year. Diagnosis: Fundus photography is necessary for patients in the early stages of diabetes. The diagnosis of DR can be made on the basis of the duration of diabetes, previous blood glucose levels and past history (onset of puberty, obesity, renal disease, systemic hypertension, lipid levels, pregnancy, etc.), combined with ophthalmologic examination and ancillary findings. Ophthalmologic examination includes best corrected visual acuity (BCVA), intraocular pressure, slit lamp microscopy (if needed), and anterior chamber angle microscopy. If necessary, anterior chamber angioscopy should be performed to rule out atrial corners neovascularization). Fundus examination is necessary after pupil dilatation, with special attention to the peripheral retina and vitreous. Ancillary tests include fundus photography, fluorescein fundus angiography (FFA), ocular coherence tomography (OCT), retinal thickness monitor, and ocular ultrasonography. Fundus photography is necessary for diabetic patients to be distinguished from early stage patients and can be used as baseline information to document the initial fundus of the patient. FFA is an important tool for diagnosis of fundus disease, and can be used for dynamic in vivo response to blood-retinal barrier function, capillary leakage, and circulation to compare the effect of whole retinal photocoagulation treatment before and after, to judge its effect and provide a basis for patching photocoagulation. oCT is more sensitive and intuitive, and is better for diagnosing macular edema (DME) and tracking the efficacy of laser photocoagulation. In the diagnosis of DR, microaneurysms, hard exudates, cotton wool spots, and neovascularization are the main signs (see figure). 74.2% of DR patients have macular degeneration, and the degree of macular degeneration can be unbalanced with other parts of the retina. At any stage of the DR disease, vascular lesions invading the macula can cause central vision loss. Diabetic macular lesions include DME, macular ischemia, macular traction. DME accounts for 96.4% of diabetic macular lesions. For clinically significant macular edema, the Early Diabetic Retinopathy Study Group (ETDRS) considers one of the following: retinal thickening involving or <500 μm from the central macular recess; hard exudate or hard exudate <500) μm from the central recess with adjacent retinal thickening; one or more retinal thickening areas ≥1 optic disc area, and any part of this lesion Any part of this lesion is <1 optic disc area from the central macular sulcus. Diabetic vitreoretinopathy (DVR) precisely describes the spatial relationship between the retinal surface and the vitreous humor. It is recommended that proliferative diabetic retinopathy (PDR) should be changed to proliferative diabetic vitreoretinopathy (PDVR) when there is vitreous blood accumulation or neovascular membrane entering the vitreous cavity. And when incomplete posterior detachment of the vitreous occurs in non-proliferative diabetic retinopathy (NPDR), it should be changed to non-proliferative diabetic vitreoretinal retinopathy (NPDVR). The American Academy of Ophthalmology and the International Academy of Ophthalmology recommended DR staging criteria in 2003 as shown in Award 1, which is simple and practical. This staging is valuable in assessing whether the nonproliferative form survives into the proliferative form. The best time to perform total retinal photocoagulation for DR is during the DR-III stage, i.e., severe NPDR. This staging criteria defines DR-0. This staging criteria defines DR-0 stage is very meaningful and clarifies the importance of regular follow-up to avoid blindness in diabetic patients. DR-l stage is also a milestone definition, i.e. once MA is detected, it means the beginning of DR. Table 1 The American Academy of Ophthalmology and the International Academy of Ophthalmology recommended DR staging criteria in 2003 DR-O No fundus lesions DR-I Mild NPDR, with only microangiomas in the fundus DR-II Moderate NPDR, with lesions between mild and severe NPDR DP-III Severe NPDR, with fundus lesions meeting one of the following conditions: more retinal hemorrhages in the latissimus retina in 4 quadrants; 2 quadrants DR- IV PDR with NVD/NVE/vitreous hemorrhage/pre-retinal hemorrhage Treatment: a long-term integrated multidisciplinary systemic project The treatment of DR is a long-term, integrated, multidisciplinary systemic project, in which the effective cooperation between internists and ophthalmologists is very important. Internal medicine treatment is the foundation, aiming to control blood glucose, blood pressure, lipid management, and treat other complications to slow down the progress of DR; reduce the hyperleakage response of retinal vessels in diabetes, reduce blood hyperviscosity, and reduce platelet hyperaggregation. Ophthalmologists also need to understand the patient's blood glucose, blood pressure and lipid status so that ophthalmology-related treatment can have the best effect; and internists also need to understand the timing of the patient's referral to ophthalmology to avoid delaying the disease. Lucentis and Avastin have been shown to significantly reduce the extent of diabetic macular edema and improve visual function. As an adjunct to vitreous surgery, vitreous cavity injection of anti-VEGF drugs can effectively reduce neovascularization and complications of vitreous surgery. Total retinal photocoagulation (PRP) is an effective treatment for DR today. Multicenter, randomized, controlled studies conducted by the Diabetic Retinopathy Study Group (DRS) and ETDRS, two major prospective clinical randomized controlled studies in the United States, have confirmed that timely laser photocoagulation reduces the risk of severe vision loss by 50% in patients with DR. Standard total retinal photocoagulation extends from 1 PD-2PD beyond the optic papilla to the fundus beyond the equator, leaving the posterior pole between the macula and the superior and inferior temporal vascular arches of the optic disc unphotocoagulated. The number of photocoagulation points ranges from 1200-1600, depending on the severity of the retinal lesion, the size of the nonperfused area, and the extent of neovascularization. The spot size should generally be 500 μm, . Within the temporal vascular arch of 200 μm, laser exposure time is mostly 0.1-0.2s, and whole retinal photocoagulation should be completed in 3-5 times. The spot interval is 1 to 2 spot diameters. The output power should be a Class III spot response. The effective photocoagulation area is the key to the success of PRP treatment, and long-term follow-up ensures that the ultimate goal is achieved. Patients are usually recommended to have their fundus reviewed by a fundus specialist at 1 month after PRP treatment, and to have their FFA reviewed at 3 months, with additional photocoagulation of neovascularization based on the FFA results. Thereafter, patients should be reviewed every 3 to 6 months. Diabetic proliferative retinopathy is the result of a race in time between diabetic vasculopathy and diabetic vitreopathy. Surgical treatment is mandatory for proliferative diabetic retinopathy. Vitreous hemorrhage, retinal detachment involving the macula, retraction and hole-derived retinal detachment, preretinal hemorrhage and fibrovascular proliferation, and early iris neovascularization are all indications for surgery.