A stroke occurs when there is a blockage or rupture of the blood vessels in the brain. Atherosclerosis is the major underlying cause of stroke. Atherosclerosis or stenosis is the narrowing of the carotid artery due to plaque build-up. This disease developed asymptomatically and reduced the blood flow from the neck to the brain and eventually to the eye, resulting in impairment. The eye is the window to the brain as the eye is connected from the brain through the optic nerve head. However, real-time assessment of ocular blood flow impairment under carotid artery stenosis is vague. Assessing the eye’s blood flow can provide information about the brain’s blood flow condition. Hence, this will indicate the brain’s blood flow. This book aims to show the impact of carotid artery stenosis, resulting in a stroke and eye blood flow.