Sight – one of the most important processes at perception of the world around. In the visual device the set of functions is used. One of them is the peripheral sight.
General information about peripheral sight
The peripheral sight is one of components of the visual device which is responsible for borders of a field of vision at their projection on a spherical surface. At this field of sight represents a certain space which is perceived by an eye only in a motionless state. The visual field is one of functions of peripheral departments of a retina which defines a possibility of the person easily to be guided in space.
Key indicator of efficiency of peripheral sight is a viewing angle of the person.
As for an indicator of a field of vision, it has concrete values which are defined by retina border. So, for example, reacts to white color of eyes only at an angle 90º - retina knaruzh, 70º - up knaruzh, 55º - up inside, 55º - inside, 50º - from top to bottom inside, 65º - from top to bottom, 90º - down knaruzh.
"The blind spot" is one of such physiological scotomas which is in area of a temporal field of vision. Along with physiological scotomas there are also angioskotoma (the tape-like "losses" arising because of the increased retikalny vessels, the closing photoreceptor cages), however they only slightly worsen peripheral sight and are considered as norm.
Those sites which drop out of a field of vision are called "scotomas".
Scotomas are divided into three views: - positive; - negative; - vibrating. Positive scotomas can be distinguished independently in the form of black spots under review. They are the first sign of injury of a retina. Negative scotomas can be detected only by inspection. The cause of such scotomas – damages of the carrying-out ways. Vibrating scotomas develop spontaneously. Generally they arise because of brain angiospasms. In case, having closed eyes, the person sees zigzag multi-colored lines outside peripheral sight, experts recommend to begin intake of spazmolitichesky medicines immediately.
The list of the problems promoting deterioration in peripheral sight
Deterioration in peripheral sight is promoted by the following problems with sight: 1. Initial stages of tumors and inflammations. At such diseases ¼ part of a field of vision can be gone. 2. Various pathologies of a retina. Depending on it the sight can worsen in different zones. For example, glaucoma promotes visual field constriction in a nose. 3. Damages of a nerve and dystrophy of a retina. The similar problem leads to visual field constriction on 5-10º from all directions, such phenomenon is called concentric visual field constriction. At this disease of people can see and read, but loses completely an opportunity to be guided independently in space. Anyway at emergence at least of the slightest hint on deterioration in peripheral sight it is necessary to address for consultation experts. Having carried out necessary surveys, they will make the correct diagnosis and will help you to keep sight.