Nature knows many examples of visual features.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 flaws. 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, which gave people the nature,imperfect, but it seems to be the most universal of all. A person is able to see well both close and far enough away. The field of view is quite wide, but at the same time we can focus on a separate object. A good perception of colors, the ability to distinguish objects with a small amount of light - all this suggests that nature has generously endowed people.
Among other things, man has andperipheral, or lateral, vision. It is less acute than the central, but also serves other purposes. With it, a person orientates himself in space, notices moving objects, can recognize an approaching 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 whole 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 by working on special methods.
Tunnel vision
In some states, there is quite arare pathology characterized by a sharp narrowing of the visible space. This phenomenon is called "tunnel vision", because a person may feel that he is looking around as if through a pipe. As a result, a serious disorientation in space can occur, in addition, a similar condition affects the patient depressingly. And it arises due to the fact that for some reason the light begins to perceive only the central part of the retina.
When does it happen?
None of the clinic of ophthalmology will not 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 if it is an organic lesion of the eye.
Also a violation of the field of view can be observeddue to injuries, retinal detachment, disturbed pathways, retinal power, 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 stretches his arms to the sides and moves his fingers, looking straight. Normal movement should be noticed.
How to treat?
Unified scheme by which doctors act,confronted with this symptom does not exist. It all depends on what caused the state in which the tunnel vision is observed. If it is a caisson disease, then the patient is placed in a pressure chamber, in the case of oxygen starvation or blood loss compensate for the deficit.
But everything is more complicated when it comes to chronicform. Fortunately, there are drugs, such as Emoksipin, 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 having experienced this for yourself, it is impossible to imagine. With proper treatment of the acute state, the negative effect quickly passes and the vision is fully restored.
If organic eye damage has gonefar away, treatment may not bring much relief. Scientists work together with doctors to solve this problem. Among the options offered are special glasses, designed on the principle of binoculars, but vice versa. This invention is not popular, because through such lenses surrounding objects seem to be very small, which does not improve the ability to orientate in space.
There is another high-techdevice that helps people suffering from disorientation due to tunnel vision. It is a camera and tiny screens in front of the eye of the beholder, on which the outlines of objects beyond the patient's view are projected. The use of this device requires some habit, but all the subjects confirmed that it became much easier for them to navigate in space.
