Diabetic retinopathy(DR)is a common clinical condition caused by hyperglycemia, leading to retinal microvascular damage and neurodegeneration. With the development of advanced technologies, handheld electrophysiology(RETeval), optical coherence tomography(OCT)and optical coherence tomography angiography(OCTA)have been extensively studied and applied in early diagnosis of DR. These technologies are non-invasive and quantifiable, assisting in DR diagnosis in a fast and convenient manner. In this review, the principles and applications of RETeval, OCT and OCTA will be discussed in detail.