Tunnel vision is a medical condition that results in a loss of peripheral vision. As a result, the patient can only see objects from within a circular field. This condition has many possible causes, including problems in the brain, some eye diseases, hallucinogenic drugs, and certain extreme activities.
Blood loss to parts of the brain can lead to tunnel vision, as can a tumor pressing against the optic never fibers. A person who is exposed to air that has been contaminated by oils and hydraulic fluids, such as may happen in an airplane, may also develop this condition. Becoming ill while in an aircraft can cause temporary vision problems.
Certain diseases of the eye may also lead to tunnel vision. Retinitis pigmentosa, an inherited condition that may ultimately lead to blindness, can be a cause. Typically, this disorder begins to show itself as night blindness, which then leads to a loss of peripheral vision, and eventually to blindness. Not all people with the disorder go blind, however.
Glaucoma, a disease affecting the optic nerve, can also cause tunnel vision. The pressure placed on the optic nerve causes the eye to lose retinal ganglion cells, which can eventually cause the patient to go blind. For some patients, a loss of peripheral vision may be experienced prior to blindness.
Use of hallucinogenic drugs can also cause damage to the brain and to the nerves, which can result in permanent or temporary tunnel vision. Extreme stress, such as that experienced during a panic attack, is another possible cause. Specific activities and sports can also cause a temporary loss of peripheral vision. Fighter pilots and acrobats, for example, may experience this problem during sustained high acceleration of one or more seconds. In this case, the person may also lose consciousness.
Exposure to oxygen at a pressure above 1.5 to two atmospheres can be toxic to the central nervous system. This most often occurs when diving. In addition to tunnel vision, this oxygen pressure can result in fatigue, dizziness, blindness, nausea, confusion, anxiety, and lack of coordination. When a loss of peripheral vision strikes a person engaged in an activity such as driving or piloting an aircraft, it can result in death, because the individual is unable to see properly.