Ophthalmologic black clouding mostly refers to transient black clouding, the onset of which is characterized by sudden painless loss of vision in one eye, starting like a black veil covering the eye, either from the top down or from the bottom up resulting in total blindness, the duration of the attack can vary from a few seconds to several minutes, and usually the vision can return to normal after the attack. Transient blackness of the eye is caused by various causes of ocular ischemia and inadequate blood supply, such as carotid artery stenosis and blockage, with arteritis, as well as when the patient has heart disease, hypertension, hyperlipidemia, cervical spine compression, or because of postural changes. If the primary disease does not resolve, transient blackouts can occur frequently and eventually lead to complete occlusion of blood vessels and severe vision loss. Another type of black clouding is a family genetic disorder, which is mostly considered to be a degeneration of lipid-like cells in the ganglion cells of the central nervous system, and usually occurs in infancy and adolescence.