Tunnel vision is the condition where the sufferer has difficulty seeing objects at the edges of the normal field of vision and can only properly focus on objects in a narrow, "tunnel-like" field.
Tunnel vision, sometimes also called "peripheral vision loss" is one of those disabilities that could have fatal implications for the sufferer, and if you have reason to believe that you have tunnel vision you should seek medical attention as soon as possible. The chances of tunnel vision being reversed are quite slim in most cases, but if the treatment is started early, aggravation of the condition to a more severe stage, or to total blindness may be prevented.
The condition itself cannot kill you, but it puts you at great risk of being run down when crossing the road, for example, or if you operate certain types of machinery, and from driving accidents.
The Causes of Tunnel Vision
Tunnel vision can be caused by a host of medical and biological conditions ranging from blood loss, alcohol consumption through to mercury poisoning and a bite from a black mamba (a type of poisonous snake). The leading causes of the condition are listed below:
When a person suffers from glaucoma the condition causes pressure build up inside the eyeball. This fluid pressure puts a strain on the retina, distorting it or warping it out of shape and the result is loss of peripheral vision, or tunnel vision. The causes of glaucoma itself are still unknown, but it can be treated and its impact on the deformation of the retina slowed or even stopped. This will not cure the tunnel vision that it leaves in its wake, but it has the effect of "arresting" the condition and preventing it from getting worse. In addition to causing damage to the retina glaucoma also may do damage to the optic nerve, and this could progress into total blindness if the nerve got too badly damaged.
Glaucoma can be treated with eye drops and other forms of medication and if your tunnel vision has been caused by glaucoma you should take the treatment of the glaucoma itself as a very high priority. Your tunnel vision problem could get much worse if you are lax with the glaucoma treatment.
Eye "Strokes" or Blocking of Blood Vessels in the Eye
If blood vessels in the eye get blocked (occluded) blood flow to internal organs in the eye and to the optic nerve gets interrupted and this can lead to loss of peripheral vision or even permanent loss of sight.
Strokes Affecting the Brain
A stroke that damages some parts of the brain can cause tunnel vision by affecting the processing of visual information. The eye itself will be perfectly okay, but the imaging information it sends to the brain is only partially processed and this could result in loss of peripheral vision amounting to tunnel vision sometimes.
A Detached (or Displaced) Retina
The retina inside the eye can get detached from its supportive layers of tissue if there is injury or shock to the eye or the head (concussion) and this is a serious condition that could lead to loss of sight in extreme cases, or to tunnel vision. A surgical operation would then be needed to re-seat the retina and if this if done early the tunnel vision may be fully reversed. A person with a detached retina will usually experience warning signs, such as flashes of light, floating points of light or black and white spots in your field of vision. In addition you might see shadows and "curtains" across the field of vision, vertical or horizontal (from left to right) where you know they should not be.
Alcohol and Hallucinogenic Drugs
Alcohol can affect the ability of the eyes to focus on the same object and also causes blurring of the vision. In other cases it can cause tunnel vision. Hallucinogenic drugs can have the same effect as alcohol, by causing damage to the eyes or the visual processing centers in the brain. The tunnel vision caused in these circumstances may be temporary or last for the duration when the drug is still in circulation. But in severe cases of poisoning of the brain the changes may become permanent.
Cataracts can reduce the area of the external membrane of the eye (the cornea) through which light can pass to reach the retina and this usually leads to tunnel vision in one or both eyes.
Some spectacles can reduce your field of vision to what amounts to tunnel vision. This is not a condition affecting the eyes themselves but is the result of the obstruction of the path of light caused by the lenses. A person in this situation may have to turn their heads every time they want to focus on an object just a few degrees to the left or right of center field.
Other Causes of Tunnel Vision
A host of other conditions can cause cases of tunnel vision that may usually be temporary. Altitude sickness in passenger aircraft may be the cause of temporary tunnel vision. Very high accelerations lasting for more than one second can also cause a temporary case of tunnel vision for pilots or passengers in very fast aircraft.
Situations that cause secretion of high levels of adrenaline such a physical fight can also cause tunnel vision. Even intense anger causes the release of high levels of adrenaline and can cause temporary tunnel vision.
Other situations that cause tunnel vision include exposure to oxygen at high pressure (such as may happen to divers), prolonged exposure to air suffused with heated vapor from hydraulic fluids (as may happen in aircraft for example), extreme fear or anxiety that leads to a panic attack, etc.
From what has been noted above the conditions, medical, biological or environmental that could cause tunnel vision are quite numerous. Anybody could at some point in their lives suffer from tunnel vision (hopefully the temporary kind!). But the permanent cases of the condition are quite debilitating, and in some cases could prove fatal. By knowing the causes of tunnel vision you reduce the risk of developing the extreme cases of the condition, by knowing when to seek medical attention if you have reason to believe that you may be getting tunnel vision. Unlike other eye problems tunnel vision cannot usually be treated by wearing glasses for example, although it has been tried with spectacles that incorporate prisms to expand the field of vision. The condition cannot usually be reversed. Where tunnel vision is concerned the best cure lies in preventing the condition.