Our article today will be devoted to vision and its work. We will note how the visual apparatus works, what peripheral vision is and what viewing angle is available to the human body.
One of the functions of the visual apparatus is peripheral vision. The peripheral parts of the retina are responsible for it . The main indicator of its productivity is the viewing angle of a person. It includes that part of the space that human vision covers while still fixing the gaze on the subject. The main function of peripheral vision is spatial orientation.
The field of view indicator has specific values determined by the border of the retina. The eye responds to white in the following limits: outward - 90º, upward outward - 70º, upward inward - 55º, inward - 55º, downward inward - 50º, downward - 65º, downward outward - 90º. "Loss" of its individual sections is called cattle. In the zone of the temporal field of view there is a physiological scotoma - the so-called "blind spot". The presence of angioscots is also natural - ribbon-like “prolapses” in the field of view associated with the presence of massive retical vessels that block photoreceptor cells. Their presence only slightly affects peripheral vision. and is considered the norm.
Scotomas are absolute, with a complete "loss" of the site, and relative - with marked deterioration in visual function in the examined interval. In turn, these two types are divided into positive and negative scotomas. Positive can be detected independently: they are visible as black spots in the field of view, which indicates damage to the retina. Negative scotomas are not subject to independent detection and appear due to damage to the pathways. They are usually detected during the examination. There are still atrial scotomas. As a rule, their appearance is not subject to any system and is completely spontaneous. If a patient with closed eyes observes zigzag multi-colored lines extending to peripheral vision, he has spasms of cerebral vessels. To stop this process and improve the situation, doctors recommend immediately starting to take antispasmodic drugs.
At the location of the cattle can be classified as follows:
- peripheral;
- paracentral;
- central.
Next, we provide a list of vision problems that contribute to the deterioration of peripheral visual perception.
The narrowing of the field of view from all sides to 5-10 degrees is a consequence of nerve damage and dystrophy of the retina. This phenomenon is called concentric narrowing of the field of view. As a rule, in such a situation, a person still sees and can even read, but the ability to navigate independently in space disappears completely and the visual perception worsens significantly.
In the event that the patient disappears symmetric portions of the review, it is worth contacting specialists for a thorough examination. Such symptoms often indicate the presence of tumors, hemorrhages and other serious diseases in the patient. At the initial stages of tumors and inflammations, only a part of the field of view may be lost, i.e. approximately a fourth of the field of vision disappears. With pathologies of the retina, vision can disappear in different areas. For example, with glaucoma the field of view is narrowed from the nasal side.
By analyzing the nature of the visual field restriction, an experienced specialist can determine the localization of the lesion in various departments of the visual pathways, as well as the degree of degenerative lesion, the stage of glaucoma and other parameters.