EYE ESTIMATION

From Big Medical Encyclopedia

EYE ESTIMATION — ability to define and compare space sizes without special measuring devices, approximately. Distinguish G. linear — ability to make relative and absolute comparison of lines and areas, and G. deep — ability to estimate a relative positioning of objects of depth or an otstoyaniye of objects from the observer. Physical are the cornerstone., fiziol, and psikhol. patterns of vision of a form, remoteness, size, direction and movement of objects of the outside world. Glazomerny estimates can be monocular or binocular. Binocular estimates more precisely than monocular.

Perception of a form of objects of subjects more precisely, than above visual acuity (see). The sizes of objects are estimated depending on the area of the image on a retina and the seeming remoteness of a subject.

Perception of remoteness, depth is caused by linear and air perspective, distribution of light and shade under review, a zagorazhivaniye of one objects others, the relative speed of shift of objects if they move, the visible size of a subject (than more familiar subject, it is closer to those), tension of accommodation necessary for accurate vision of a subject. At binocular perception essential value has so-called binocular parallax (see. Solid vision ). Assessment of the direction of a subject in relation to the observer depends on the place on a retina, on a cut the optical image of a subject falls.

Allows to judge as the valid, and seeming movement of objects. Perception of the movement of a subject arises or owing to change of the place of irritation on a retina (at a motionless look), or owing to movement of a look at keeping track of by a moving subject.

Results of glazomerny assessment are quite often influenced by various visual or optical illusions (see. Visual illusions ). Owing to contrast small objects among big seem smaller, than they are actually and vice versa. If rate of strain accommodations of an eye (see) it is inadequate to remoteness of a subject, it seems or reduced (a micropsia at a spasm of accommodation), or increased (a macropsia at paresis of accommodation). Usually with very high precision parallelism of two lines, the slightest break or a bend on a separate straight line, right angles, identity or similarity of objects of a form is estimated. The vertical sizes and acute angles are, as a rule, revaluated, and lateral dimensions and obtuse angles are underestimated. The distances filled with objects seem big, than blank. Straight lines in a peripheral part of a field of vision are represented bent.

The reasons of optical illusions are various: not clear perception of objects, disturbances of accommodation, the movement of eyes, psikhol, influences, etc.

of G. plays an important role in life and during the performance of many works, especially at glazomerny shootings. G.'s accuracy depends on features of an organ of sight and fitness of the person. Considerably improves as a result of systematic trainings, napr, drawing, drawing, sports. At adverse meteorol, conditions, at the lowered illumination, in a condition of exhaustion glazomerny function worsens.

Value of an eye estimation in military science

Performance of fighting problems of various character and tasks of material, medical and other types of providing troops often demands glazomerny determination of distances on the area.

Glazomerny assessment of distance to 1000 — 1500 m the military personnel of land forces applies distances to determination of distance of efficiency of use of small arms or a throwing of the grenade, to a dash at one time or to a throw in the attack, height of obstacles, width of natural and artificial barriers, water boundaries etc. For staff of medical service G. it is necessary for determination of distance to wounded in the battlefield, at the choice of places of the shelter during their carrying out to places (nests) of gathering of wounded, at rescue and evacuation of victims from hard-to-reach spots by helicopter in the mode of hanging, reconnaissance of the area and trace of platforms for expansion of first-aid posts and to lay down. institutions in field conditions and in other cases. During general and medical investigation often it is required to make quickly and precisely glazomerny shooting of the area, to draw the plan with drawing the most important objects (bridges, roads, the rivers, structures, a forest edge, weapon emplacements and positions of the opponent etc.) and rather exact indication of distance to them from the observer. In the listed cases static G. — the observer most often is applied and objects are not mobile. Often use dynamic G. when either the observer, or an object, or the observer and an object are in the movement. So, G. allowing to estimate in the movement the speed of military equipment, distance between cars, depth and width of obstacles in roads, a possibility of their overcoming and to define detours is in most cases necessary for drivers of transport and fighting vehicles. Glazomerny assessment of distances from the airplane has the features. Conducting air fight, firing at land and air targets, weeds a system and at small heights and especially during the performance of the most responsible element of each flight — plane landing demands from the pilot of exact glazomerny assessment of distances. In flight at big speeds exact glazomerny assessment of distance to an observed object (the earth, other airplane, etc.) during short intervals of time in the absence of intermediate points of comparison of pieces or a possibility of direct observation of all defined distance it is especially difficult.

In navy exact determination of distances at the sea also has the features caused by the fact that it is necessary to observe on undivided intermediate objects space and at much smaller dust content of air. Such conditions lead to understating glazomerno of the defined distances.

Main ways of determination of distance approximately: 1) in size of familiar local objects and objects of military equipment; 2) on degree of visibility of details of the local objects which are in the neighbourhood with the purposes; 3) on the pieces received as a result of division of a distance between the observer and the purpose. Glazomerny assessment of distances with an adequate accuracy demands a careful preliminary training by purposeful exercises. The distance is measured by eye surely and more precisely when all surface is visible, on a cut the interesting objects are located. If it is observed on the cross-country terrain and the surface is looked through not completely, then the accuracy of glazomerny assessment of distance decreases. Therefore at height the review of the area is wider and G.'s accuracy is higher.



Bibliography: V. V. wolves, A. I. Gorban and Dzhaliashvi-l and O. A. Klinicheskaya vizo-and refractometry, page 7, etc., L., 1976; Glezer V. D. and d river. Visual identification and its neurophysiological mechanisms, L., 1975, bibliogr.; To r and in to about in S. V. Glaz and his work, page 414, M. — L., 1950; L of e at sh and-v N and L. I. O a ratio of visual and oculomotor systems in space perception, in book: Motor components of sight, under the editorship of B. F. Lomov and N. Yu. Ver-gilesa, page 151, M., 1975, bibliogr.; The multivolume guide to eye diseases, under the editorship of V. N. Arkhangelsky, t. 1, book 1, page 470, M., 1962, bibliogr.; H e-r i n g E. Spatial sense and movements of the eye, Baltimore, 1942; Schober H. Das Sehen, Bd 1 — 2, Lpz., 1960 — 1964, Bibliogr.; Tommilla U. Stereoscopic and binocular vision, in book: Functional examinations in Ophthal., pt 1, p. 90, Basel a. o. 1974, bibliogr.

H. A. Vishnevsky; Yu. V. Kamenshchikov (soldier.).

Яндекс.Метрика