Tunnel vision
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Normal vision. Courtesy NIH National Eye Institute
The same view with tunnel vision from retinitis pigmentosa.
Tunnel vision is a visual problem or symptom of another problem which produces loss of peripheral vision, as illustrated.
Tunnel vision can be caused by:
- retinitis pigmentosa, a disease of the eye.
- sustained (1 second or more) high accelerations, resulting in peripheral light loss. [1] (http://www.vnh.org/FSManual/02/02SustainedAcceleration.html). Can occur in fighter pilots during combat or testing situations. More severe symptoms can include loss of consciousness.
- hallucinogenic drugs.
- glaucoma, a disease of the eye.
- altitude sickness, hypoxia in passenger aircraft [2] (http://www.house.gov/transportation/aviation/06-05-03/friend.html)
- exposure to oxygen at a partial pressure above 1.5-2 atmospheres, producing central nervous system oxygen toxicity, notably while diving. [3] (http://www.vnh.org/FSManual/01/10OxygenToxic.html) Other symptoms can include dizziness, nausea, blindness, fatigue, anxiety, confusion and lack of coordination.
- other loss of blood to the brain.
- prolonged exposure to air contaminated with heated hydraulic fluids and oils, as can sometimes happen in passenger aircraft [4] (http://www.house.gov/transportation/aviation/06-05-03/friend.html).
When combined with piloting an aircraft, driving, crossing roads or operating heavy machinery, the consequences have been known to be fatal.
The expression "tunnel vision" may also be used as a metaphor for narrowmindedness or to describe researchers or investigators (such as police detectives) who pursue an investigation with their conclusion already decided and proceed by only accepting evidence that supports their conclusion and excluding any evidence that contradicts their assumptions.