The retinal neurosensory layer is an important feature in diagnosing Alzheimer's Disease (AD). As one part of the central nervous system, the retina can be imaged non-invasively with high resolution. In this review, we summarized the research advance in AD and the retina in recent years, and early warning of AD by studying the relationship between β-amyloid protein and tau protein in the retina, optic nerve, the hippocampus and the brain. Among these features, hyperphosphorylated tau, neuronal degeneration, retinal thinning, vascular abnormalities, and linear correlations between retinal and cerebral β-amyloid protein concentrations and plaques were observed. The retina is part of the central nervous system tissue, which itself, as well as the macula and surrounding vascular tissue, can provide insight into AD, such as retinal thickness, vascular abnormalities, and surrounding cells and their release. During the study, optical coherence tomography (OCT) and positron emission tomography (PET) were used to observe the retinal thickness and β-amyloid plaques, so as to understand the progress of AD. Although there is currently no effective cure for AD, the detection of various parameters and the discovery of correlations among them, for example, by the discovery of retinal thickness thinning, may help to improve the early diagnosis of AD.