Fundus color photography, fluorescein fundus angiography (FFA0), optical coherence tomography (OCT) and other medical digital imaging instruments have emerged to provide a broader space for ophthalmologists in DR clinical diagnosis and treatment, and also provide a more powerful means of tracking observation, promoting the transformation of clinical diagnosis and treatment mode. However, these testing instruments have their own advantages and disadvantages: ophthalmoscopy, including direct and indirect fundoscopy, is the most basic method of fundus examination, the instrument is inexpensive, with the advantages of rapid, convenient, accurate, no loss of information, small pupil direct fundoscopy under a single field of view is small, the need to constantly adjust the direction of examination and the patient’s eye rotation to cooperate, indirect fundoscopy imaging is inverted, the need to dilate the pupil, these two instruments The rapid diagnosis formed by these two instruments requires the examiner to have richer a priori knowledge and be skilled in DR clinical differential diagnosis, which objectively cannot be preserved and is not conducive to follow-up observation and comparative diagnosis. Fundus photography can quickly obtain color images of the fundus in different fields of view, contains in vivo information and features, is intuitive and clear, highly accurate, more comprehensively reflects retinal damage in the posterior pole, and has a digital preservation function, which is convenient for regular comparative observation. FAA reflects the state of retinal barrier damage from the perspective of retinal vascular circulation physiology. High-definition camera technology can dynamically capture the circulation state of retinal capillaries, and intermittent or continuous acquisition can form static black-and-white images of the retina or dynamic small film information, which is highly sensitive in the early diagnosis of DR and has a high confirmation rate, and can detect deep retinal microvascular tumors that are not easily detected under ophthalmoscopy or fundus photography. It is the “gold standard” in the diagnosis and treatment of fundus disease. It has the unique advantage of being able to determine the extent and size of the non-perfused area of the retina and the nature of neovascularization from fluorescein leakage patterns. However, the test is invasive, time-consuming and labor-intensive, with allergic reactions, and its clinical application is limited, making it unsuitable for large-scale screening. OCT is a direct measurement of retinal morphology with microscopic level resolution (within 10 μm), which can section the thickness changes of retinal nerve fiber layer, and can detect minor macular edema caused by DR that is not easily detectable by examining glasses, fundus photography and FFA, and has the advantage of being quick and risk-free without dilating the pupil, but cannot determine the presence or absence of microangioma, and has no guiding value for retinal laser photocoagulation. In conclusion, routine ophthalmoscopy combined with fundus photography, or combined with OCT and FFA, can significantly improve the ophthalmologist’s level of prevention and treatment of retinal diseases, and achieve early diagnosis and effective treatment.