Dizziness and blackness when getting up from squatting for a while is due to the development of postural hypotension, resulting in a transient cerebral blood supply deficit. When the patient is in the squatting position, the muscles of the lower extremities are squeezed and in a contracted state, when most of the blood is concentrated in the upper body, and because of the patient’s reduced altitude, the heart only needs less power and lower blood pressure to maintain an adequate blood supply to the brain. If the patient suddenly stands up, the leg muscles relax and are able to accommodate more blood, the blood flow will suddenly rush to the lower body due to gravity, resulting in a relative decrease in blood supply to the brain. At this time, blood pressure is already low, and if the heart cannot strengthen pumping and constrict blood vessels in time, the blood supply to the brain will be even more inadequate, causing symptoms of whole brain ischemia. Posterior circulation ischemia will cause dizziness, and anterior circulation ischemia will cause blackness in front of the eyes when the ophthalmic artery is involved.