Alzheimer's disease(AD)is one of the most common causes of Dementia in the world, with symptoms often appearing years after the degenerative changes in the brain. Therefore, the early diagnosis of AD is difficult and the previous diagnostic methods are generally invasive. Considering that most patients with AD are accompanied by visual impairment, the retina can be regarded as a window into the brain. Recently, optical coherence tomography(OCTA)can be used for noninvasive and rapid assessment of structure within different vascular plexuses in the retina and choroid. This improves our understanding of neurological diseases, and more likely contributes to the early diagnosis of AD patients. This paper reviewed the relevant literatures on the application of OCTA in the study of neurological diseases, as well as the structure and function of the brain and retina in patients with AD.