What is “transient blackness”? Many patients who visit the ophthalmology department feel that they have sudden difficulty seeing in one or both eyes, and then recover naturally after a few minutes to an hour. The ophthalmology clinic refers to this phenomenon as “transient blackness”. Let’s understand together what “transient blackness” is all about. “Transient blackness” is also known as “transient visual loss (TVL)”. The traditional definition of TVL is a sudden onset of vision loss in one or both eyes, without new neurological signs and symptoms, that resolves completely on its own within 24 hours. The new definition of TVL is “a sudden onset of vision loss in one or both eyes without other emerging neurological signs and symptoms that resolves spontaneously within one hour. It is important to note that TVL is an isolated event with no other new neurological signs or symptoms. Pathogenesis of TVL: 1. Carotid (internal) artery disease:severe stenosis of carotid artery, atherosclerotic plaque and carotid artery entrapment aneurysm can lead to intravascular embolus and TVL, which migrates to ophthalmic artery or retinal artery with blood flow and can lead to vision loss. In some cases, the dislodged embolus moves to the distal small artery and embolizes the distal small artery, and the embolus can autolysis soon after partial embolization, and a typical 2. In addition, cardiogenic embolic TIA is caused by the embolus of cardiac origin (such as atrial fibrillation) entering the middle cerebral artery, posterior cerebral artery or ophthalmic artery causing vascular obstruction, and if the embolus autolyses, cardiogenic TVL is formed. TVL caused by carotid artery disease is manifested as monocular TVL, and the loss of vision in one eye usually lasts less than 30 minutes; TVL caused by carotid artery entrapment aneurysm is manifested as monocular 3, vascular disease: on the basis of severe arterial stenosis blood pressure fluctuations lead to the distal posterior cerebral artery or ophthalmic artery transient undersupply, blood pressure is below the threshold of cerebral perfusion loss, then the typical TVL occurs. blood pressure increases cerebral perfusion recovery when the symptoms relieve.