Nature knows many examples of the characteristics of vision in animals. Some species notice only moving objects, others perceive only certain colors. In this sense, a person is lucky to get the most universal visual apparatus, although he is not without some drawbacks. For example, we have developed the so-called peripheral, or lateral, vision. Sometimes it fails. In what cases?
About human peripheral vision
The structure of the eye that nature has given to people is imperfect, but it seems to be the most universal of the existing ones. A person is able to see well both close and at fairly long distances. The field of view is quite wide, but at the same time we can focus on a separate object. Good color perception, the ability to distinguish objects with a small amount of light - all this gives reason to believe that nature has generously endowed people.
Among other things, a person has peripheral, or lateral, vision. It is less acute than central, but also serves other purposes. With it, a person navigates in space, notices moving objects, can recognize imminent danger, etc. This is possible due to the special structure of the retina, the cones on which are located not only in the central part, but also on the periphery, although they are much smaller. The entire field of view includes up to 180 degrees horizontally and about 130 vertically. Specific values vary from one person to another, in addition, this ability can be trained using special techniques.
Tunnel vision
In some conditions, a rather rare pathology is observed, characterized by a sharp narrowing of the visible space. This phenomenon is called "tunnel vision", since it may seem to a person that he is looking around as if through a pipe. As a result, serious disorientation in space may occur, in addition, a similar state acts depressingly on the patient. And it arises because for some reason light begins to perceive only the central part of the retina.
When does it happen?
Not a single ophthalmology clinic will help if you do not identify the cause of this extremely unpleasant condition. And they can be very diverse:
- oxygen starvation;
- severe blood loss;
- sharp pressure drop;
- hallucinogens and some other drugs;
- a sharp release of norepinephrine (“hit or run” reaction);
- nitrogen poisoning (decompression sickness) ;
- complications of laser therapy;
- cataract;
- glaucoma;
- retinal degeneration.
Depending on what caused the effect, tunnel vision can be either fast-passing or permanent in nature when it comes to organic eye damage.
Also, a violation of the field of view can be observed due to injuries, detachment of the retina, violation of the pathways, nutrition of the retina, damage to the optic nerve, etc. By the way, there is a simple test that allows you to check peripheral vision, which can be done independently. The subject simply extends his arms to the sides and moves his fingers, looking directly. Normally, movement should be noticed.
How to treat?
There is no single scheme by which doctors who deal with such a symptom act. It all depends on what caused the condition in which tunnel vision is observed. If this is a caisson disease, then the patient is placed in a pressure chamber, in the case of oxygen starvation or blood loss, the deficiency is compensated.
But everything is more complicated when it comes to the chronic form. Fortunately, there are drugs such as Emoxipin, Taufon, etc., which have a beneficial effect on the restoration of peripheral vision. In addition, lutein also helps in this matter, although it is usually not easy to completely stop the process.
Forecast
Tunnel vision is not just discomfort. A person actually loses the ability to move independently, but without experiencing this on himself, it is impossible to imagine. With proper treatment of an acute condition, the negative effect quickly passes and vision is completely restored.
If organic eye lesions have gone far, treatment may not bring significant relief. Scientists are working together with doctors to solve this problem. Among the proposed options there are special glasses designed according to the principle of binoculars, but vice versa. This invention is not popular, because through such lenses the surrounding objects seem very small, which does not improve the ability to orientate in space.
There is another high-tech device that helps people suffering from disorientation due to tunnel vision. It consists of cameras and tiny screens in front of the beholder’s eyes, onto which the outlines of objects that are beyond the scope of the patient’s vision are projected. Using this device requires some habit, but all subjects confirmed that it became much easier for them to navigate in space.