Tunnel vision can be caused by:
- Glaucoma, a disease of the eye.
- Retinitis pigmentosa, a disease of the eye.
- Blood loss (hypovolemia)
- Alcohol consumption. In addition, the vision becomes blurred or double since eye muscles lose their precision causing them to be unable to focus on the same object.
- Sustained (1 second or more) high accelerations. Typically, flying an airplane with a centripetal acceleration of up to or over 39 m/s2 (4gs) with the head towards the center of curvature, common in aerobatic or fighter pilots. In these cases, tunnel vision and greyout may proceed to a g-force induced Loss Of Consciousness (g-LOC).
- Hallucinogenic drugs, in particular the dissociatives.
- Extreme fear or distress, most often in the context of a panic attack.
- Excitement or extreme pleasure such as on a roller-coaster, causing a surge of adrenaline in the body.
- During periods of high adrenaline production, such as an intense physical fight.
- Altitude sickness, hypoxia in passenger aircraft
- Exposure to oxygen at a partial pressure above 1.5-2 atmospheres, producing central nervous system oxygen toxicity, called narcosis. Other symptoms can include dizziness, nausea, blindness, fatigue, anxiety, confusion and lack of coordination.
- Pituitary tumours (or other brain tumours that compress the optic chiasm)
- Prolonged exposure to air contaminated with heated hydraulic fluids and oils, as can sometimes happen in passenger aircraft.
- Severe cataracts, causing a removal of most of the field of vision
- During the aura phase of a migraine
- Intense anger, due to the body being rapidly flooded with adrenaline and oxygen
- A bite from a black mamba and other snakes with the same strength venom.
- Mercury poisoning (especially methylmercury)
- Sleep deprivation
This unsharp tunnel is blurred vision, obviously.