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Temporary blindness can be caused by bright flashes of light, medical conditions, or psychological factors. Flash blindness is common and caused by oversaturated pigments in the retina. Heart and cardiovascular problems can also cause temporary blindness, and some devices are designed to induce it for defense or attack purposes.
Temporary blindness, also known as fleeting blindness, is loss of vision that lasts for only a limited amount of time. It can be linked to many causes, from bright flashes of light to more serious medical conditions, such as increased pressure on the brain or optic nerves. People often find temporary blindness disconcerting and can be problematic if it starts suddenly. People who drive or engage in other activities that require vision can put themselves and others in great danger if their vision is suddenly impaired.
Flash blindness, or blindness caused by a sudden, bright flash of light, is among the most common forms of temporary blindness. Most people experience this to varying degrees at some point in their lives. A camera flash or going from a dark room to a bright outdoors can often lead to flash blindness. It is caused when the pigments in the retina, responsible for perceiving light, become oversaturated or bleached out. Flashes tend to lead to especially severe flash blindness at night when the pupils are dilated, allowing a large amount of light into the retinas.
There are many internal conditions unrelated to light that can also lead to temporary blindness. Some conditions cause fluid to build up in the brain; this can lead to pressure affecting the nerves and cavities that are essential for vision. Blindness persists until such fluids are removed. In some individuals, migraines can also lead to this symptom.
Psychological factors can, in rare cases, cause loss of vision over a period of time. This tends to occur during times of high emotional stress. This phenomenon is known as conversion: the brain converts a psychological problem into a physical form.
Some heart and cardiovascular problems can lead to temporary blindness. One such condition is aortic dissection, in which a tear in the aortic wall causes blood to flow into the aortic wall. This changes some properties of the blood that flows in the rest of the body and in the brain. As a result, the wrong amount of oxygen reaches the parts of the brain that control vision, so vision is lost.
There are some devices which, for the purpose of defense or attack, are used to deliberately induce temporary blindness. There are some explosives used by military and police forces which are specifically designed to create brilliant flashes of light to blind enemies. Some individuals carry sprays such as pepper spray which, when applied to an attacker’s eyes, induce blindness.
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