Alzheimer's disease(AD)is a common degenerative disease of the central nervous system in which neuropathological changes precede cognitive dysfunction and behavioral impairment. Currently, early diagnosis of AD is based on invasive and expensive testing techniques that are difficult to use widely in the clinical setting. Therefore, there is an urgent need for new markers to detect AD at an early stage. The eye, as an extension of the brain, has been found to show earlier onset of ocular pathologic changes in patients with AD compared to brain pathologic changes, such as retinal structural abnormalities, visual dysfunction, retinal abnormal protein accumulation, choroidal thickness changes, decreased corneal nerve fiber density, deposition of abnormal Aβ proteins in the lens, and pupillary light decreased sensitivity of response, etc. This article reviews the ocular pathologic changes in AD patients in recent years to provide new ideas for the early clinical diagnosis of AD.