From Big Medical Encyclopedia

SOLID VISION (Latin bin[i] on two, couple + oculus of eyes) — sight two eyes and receiving at the same time the uniform combined vision. B. z. it is carried out by the joint activity of touch and motor systems of both eyes providing the simultaneous direction of visual axes on subject to fixing, merge of monocular images of this object in a uniform visual object. As a result of such joint activity of both eyes the visual analyzer receives new quality — ability to precisely estimate the third space measurement, depth of space.

Touch basis of B. z. makes the mechanism of correspondence of retinas and fuziya (see). Its essence consists that single perception of the considered object is possible only on condition of simultaneous irritation of the central poles of retinas or points of the retinas symmetrized in relation to the central poles. It is so-called identical, or corresponding, points of retinas. If the image of an object gets on asymmetrical (disparatny) points of retinas of both eyes, then there is a doubling. The last is a source of optomotor reflex of a fuziya (a fuziya — merge of the images of the fixed subject received on a mesh cover of the left and right eye in a uniform visual object which is perceived volume, in three dimensions), as a result to-rogo an eye makes the adjusting movement, and the image in an eye moves to the corresponding point of a retina again.

Fig. 1. Dot horopter: and — a point of fixing; in — nodal points of eyes; and 1 and and 2 — central poles of mesh covers; — one of points of a horopter which is projected on identical points of mesh covers 1 and 2 (simultaneous excitement of the last would cause single perception of a point). Fig. 2. Sohn Panum: and — a point of fixing; a1 and a2 — the central poles of mesh covers; — one of points of a zone which is projected on geometrically nonidentical points of mesh covers b1 and b2 (simultaneous excitement of the last would cause single perception of a point); in — a nodal point of an eye.

Geometrical creation shows that in the conditions of this binocular fixing set of the points of space falling on identical points of retinas shall be located on the circle which is carried out through a point of fixing and nodal points of both eyes. It is a so-called dot horopter (fig. 1). However such «geometrical» correspondence of retinas represents only an inborn basis for joint coordinate work of both eyes. At the created B. z. the «functional» correspondence of retinas allowing single perception of the points several going beyond the line of a horopter and located within a so-called zone of Panum takes place, edges it is close in a form to an ellipse and gradually extends from a point of fixing to the periphery (fig. 2).

Fig. 3. Scheme of physiological doubling: F — a point of fixing; B — near and D — distant points under review; f1, b1, d1 and f2, b2, d2 — images fixed, near and far points on a mesh cover of the right and left eye; B1, B2 and D1, D2 — an arrangement near and far points of the right and left eye in a binocular field of vision.

Because two optical receptors are in the frontal plane and on nek-rum distance from each other, on each of them even within Panum's zone not quite similar images of objects of the outside world lay down. Besides, in the conditions of this fixing a part of space is located ahead of or behind a point of fixing, within Panum's zone or out of it, i.e. is inevitably projected not on corresponding, and on disparatny points of retinas, causing so-called physiological doubling (fig. 3). In usual conditions this physiological doubling is neutralized, not felt, but serves as a prearranged signal of perception of the third space measurement.

Feeling of depth of space at B. z. it is carried out by means of the mechanism of binocular parallax (a difference between sizes of the corners which are formed during the fixing by two eyes of distant and closer objects). The size and the provision of an angle of binocular parallax serve as a criterion of relative remoteness of objects. If the big angle of binocular parallax lies in a temporal half of a retina, then the subject seems located closer fixed if this corner is in a nasal half of a retina, the subject seems located further. To the temporal provision of a corner there corresponds the feeling of smaller remoteness, to nasal situation — bigger remoteness of objects. Assessment of the deep space relations occurs on the basis of the analysis and synthesis in a cerebral cortex of the known combination of the irritations going from mesh covers and eye muscles.

As ideas of distribution of treatments of light and shade, of the relative size of objects, feeling of air and space perspective etc. at the same time contact the specified combination of irritations — all these so-called secondary factors of deep sight can provide to a certain extent the correct assessment of the third space measurement and at monocular sight, i.e. in the absence of primary factor of perception of depth — binocular parallax.

For judgment of B.'s presence z. and quantitative assessment of a condition of deep sight a number of devices is offered (tsvetotest Belostotsky — Friedman, Howard's devices — Dolman, Litinsky, etc.).

See also Leading eye , Sight , Convergence of eyes , Field of vision .

Bibliography: Avetisov E. S. Disbino-kulyarnaya amblyopia and its treatment, page. And, M., 1968; Kogan A. I. Binocular system and perception of three-dimensional space, in book: Fiziol, touch systems, under the editorship of G. V. Gershuni, page 279, JI., 1971, bibliogr.; To r about p m and I. L. Fiziologiya's N of solid vision and its frustration at a concomitant strabismus, L., 1966, bibliogr.; Adler F. H. Adler’s physiology of the eye, clinical application, Chicago, 1970; System of ophthalmology, ed. by S. Duke-Eider, v. 4, L., 1969.

Avetisov E. S.