COLOR SIGHT

From Big Medical Encyclopedia

COLOR SIGHT (synonym: color sensation, colors distinguishing, a chromatopsia) — ability of the person to distinguish color of visible objects.

Color makes impact on the general psychophysiological condition of the person and to a certain extent influences his working capacity. Therefore the great value is attached to color registration of the rooms, the equipment, devices and other objects surrounding people on production and in life. Optimum impact on sight is exerted by low-saturated colors of a middle part of a visible range (yellow-green-blue), so-called optimum colors. For the color alarm system use, on the contrary, saturated (safety) colors.

Color — property of light to cause a certain visual feeling according to spectral structure of the reflected or emitted radiation. Distinguish seven primary colors: red, orange, yellow, green, blue, blue and violet. Depending on the wavelength of light allocate three groups of flowers: long-wave (red, orange-red, orange), mediumwave (yellow, flavovirent, green) and short-wave (blue, blue, violet).

Colors divide on chromatic and achromatic. Chromatic colors have three main qualities: a color tone,

to-ry depends on the wavelength of light radiation; the saturation depending on a share of the main color tone and impurity of other color tones; brightness of color, i.e. degree of its proximity to white color. Various combination of these qualities gives a big variety of shades of chromatic color. Achromatic colors (white, gray, black) differ with only brightness.

During the mixing of two spectral flowers with different wavelength the resulting color is formed. Each of spectral flowers has a complementary color, during the mixing about the Crimea the achromatic color — white or gray is formed. The variety of color tones and shades can be received by optical mixing of only three primary colors — red, green and blue. The amount of the colors and their shades perceived by an eye of the person is extraordinary high and makes several thousands.

Physiology of C. h. it is insufficiently studied. From the offered hypotheses and theories of C. h. the greatest distribution was gained by the ternary theory, original positions a cut were for the first time stated by M. V. Lomonosov in 1756. Further these provisions were confirmed and developed by Jung (T. Young, 1802) and G. Helmholtz (1866). According to the ternary theory of Lomonosov — the Ship's boy — Helmholtz in a retina of an eye is available three perceiving devices (a receptor, an element), to-rye are excited in different degree under the influence of light irritants of various wavelength (spectral response of an eye). Each type of a receptor is excited preferential by one of primary colors — red, green or blue, however to some extent reacts also to other colors. Therefore curves of spectral response of separate types of tsvetovosprinimayushchy receptors are partially imposed at each other. The isolated excitement of one type of a receptor causes a feeling of primary color. At equal irritation of all three types of receptors there is a feeling of white color. In an eye there is primary analysis of a radiation spectrum of the considered objects to separate assessment of participation in them of red, green and blue spectral ranges. In a cerebral cortex there is a final analysis and synthesis of light influence which are carried out at the same time. Thanks to such device of the visual analyzer of people can distinguish a set of color shades rather well.

Ternary theory of C. h. confirm data of morpho-physiological researches. Spektrofotometrichesky researches allowed to define absorption spectrums of various types of single photoreceptor cells. According to Dow (N. W. Daw, 1981), rhodopsins (see) flasks of a retina of the person have the following maxima of absorption spectrums: krasnochuvstvitelny — 570 — 590 nanometers, zelenochuvstvitelny — 535 — 555 nanometers and sinechuvstvitelny — 440 — 450 nanometers. The modern electrophysiologic researches of an organ of sight conducted by L. P. Grigorieva and

A. E. Fursova (1982) also confirmed the ternary theory of color sight. They showed that to each of three color irritants there corresponds a certain type of biopotential of a retina and visual area of a cerebral cortex.

There are also other theories of C. h., not gained, however, wide recognition. According to the oiionentny theory of color sight of Goering allocate three couples of opposite

flowers: red and green, yellow and blue, white and black. To each couple of flowers in a retina there correspond special — red-green, yellow-blue and white-black substances. Under the influence of light there is a destruction of these substances (dissimilation), and in the dark — recovery (assimilation). Various combinations of processes of dissimilation and assimilation create variety of color impressions. Goering's theory does not explain a number of the phenomena, in particular disorders of color sight. The ionic theory of Lazarev (1916) connects color perception with allocation of the ions exciting tsvetorazlichitelny receptors. According to its theory flasks of a retina contain three light-sensitizing agents: odes

COLOR SIGHT 147


but from them absorbs preferential red light, another — green, the third — blue; at light absorption these substances break up with allocation of ions which excite tsvetorazlichitelny receptors. The polychromatic theory of Hartridzha assumes existence of seven types of receptors.

At the person distinguish night, or scotopic, sight, twilight, or mezopichesky, and day, or photopic, sight (see). It is caused first of all by existence in a retina (see) eyes of the person of two types of photoreceptors — flasks and sticks that formed a basis for justification of the theory of the duality of sight which is put forward to Shulttsa (M. to J. Schultze, 1866) and further developed by M. M. Voinov (1874), Parino (H. Pari-naud, 1881) and Chris (J. Kries, 1894). Flasks are located, hl. obr., in the central department of a retina also provide photopic sight — perceive a form and color of the objects which are under review; sticks are located in peripheral department, provide scotopic sight and find weak light signals on the periphery of a field of vision.

The maximum of spectral response for flasks is in a zone of 556 nanometers, and for sticks — in a zone of 510 nanometers. In spectral response of flasks and sticks Purkinye's phenomenon which is that in the conditions of weak lighting green and blue colors seem is explained by this distinction is lighter red and orange while in the conditions of day lighting these colors on lightness are approximately identical.

Force of a color irritant and a color contrast exerts impact on perception of color. For color discrimination brightness (lightness) of a surrounding background matters. The black background strengthens brightness of color fields since they look lighter, but at the same time weakens color a little. The color perception of objects is influenced significantly also by chromaticity of a surrounding background. Figures of the same color on a yellow and blue background look differently. This phenomenon of a simultaneous color contrast.

The consecutive color contrast is shown in vision of a complementary color after influence approximately of primary color. E.g., after examining of the green lamp shade of a lamp white paper at first seems painted in reddish color. At long influence of color decrease in color sensitivity, owing to color «exhaustion» of a retina is approximately noted, up to such state when two different colors are perceived as identical. This phenomenon is observed at persons with normal C. h. also is physiological. However at defeat of a macula lutea of a retina, neuritis and an atrophy of an optic nerve of the phenomenon of color exhaustion come quicker.

According to the ternary theory of C. h. the normal color sensation is called a normal trikhromaziya, and persons with normal C. h. — normal trichromats. Quantitatively color sight is characterized by a threshold of color sensation, i.e. the smallest size (force) of the color irritant perceived as a certain color.

Disturbances of C. h. can be inborn and acquired. Inborn disorders of color sight are observed more often at men. These disturbances are, as a rule, stable and come to light in both eyes, sensitivity is more often lowered to red or green colors. In this regard with initial disturbances of color sight carry the persons though who are distinguishing all main spectral colors, but having the lowered color sensitivity, i.e. the raised thresholds of color sensation to group.

Classification of inborn disorders of color sight of Chris — Nagel provides three types of disturbances of color sight: 1 — an abnormal trikhromaziya, 2 — a dichromasia, 3 — a monochromasia. Depending on the wavelength of a light irritant and its arrangement in a range, tsvetovosprinimayushchy receptors designate the Greek words: red — protos (first), green — deyteros (second), blue — tritos (third). According to it at an abnormal trikhromaziya distinguish weakening of perception of primary colors: red — about -

a tanomaliya, green — a deyteranokhma-liya, blue — a tritanomaliya. The dichromasia is characterized by deeper disturbance of C. h., at Krom completely there is no perception of one of three flowers: red

(protanopia), green (deuteranopia) or blue (tritanopia). The monochromasia (achromasia, achromatopsia) means lack of color sight, color-blindness; at the same time only black-and-white perception remains. In addition to this classification (1937) by E. B. Rabkin at a protanomaly and a deuteranomaly three extents (type) of disturbances of C are allocated. h.: sharp disturbance — type A, moderated — type B and a lung — type C.

Inborn frustration of C. h. it is accepted to call daltonism, by name the English scientist J. Dalton who was suffering from disturbance of perception of red color and described this phenomenon.

In the most frequent C among inborn frustration. h. (to 70%) the abnormal trikhromaziya is. Inborn disturbances of C. h. are not followed by disorder of other visual functions. Persons with inborn frustration of C. h. usually do not show complaints, and disturbances of color sight come to light only at a special research.

The acquired frustration of C. h. meet at diseases of a retina (see), an optic nerve (see) or c. N of page; they can be observed in one or both eyes, usually are followed by disturbance of perception of all 3 flowers, proceed in combination with other disorders of visual functions. The acquired frustration of C. h. can be shown in the form of a xanthopsia (see), blue visions and red visions (see). The xanthopsia — vision of objects in yellow color, is observed at jaundice, poisoning with nek-ry substances and .lekarstvenny means (picric to - that, santonin, quinacrine, amyle nitrite). Blue vision — perception of objects in blue color, is observed after removal of a cataract (see). Red vision — disturbance of vision, at Krom visible objects are represented painted in reddish color. It is observed at persons with normal color perception as a result of long fixing of an eye on a light source bright, rich with UV rays, and also after operation of removal of a cataract. Unlike inborn disturbances of color sight which are constant the color sight changed as a result of the listed above diseases is normalized in process of their treatment.

148 COLOUR SENSATION

As a number of professions demand preservation of normal color sensation, napr, from the persons occupied on all means of transport in nek-ry industries, the military personnel of separate types of military forces, to them conduct an obligatory research C. h. For this purpose apply two groups of methods — pigmental and spectral. Carry researches by means of color (pigmental) tables and various test objects to pigmental (sets of multi-colored hanks of wool, pieces of a cardboard, etc.), to spectral — a research by means of spectral anomalscopes. The principle of a research of color sight by means of color tables was offered by J. Stilling. From color tables the greatest distribution was gained by polychromatic tables of Rabkin. The basic group of tables is intended for differential diagnosis of forms and extent of inborn frustration of C. h. and their differences from acquired; control group of tables — for specification of the diagnosis in difficult cases. In tables among background circles of one color there are circles of identical brightness, but other color tone making any figure or a figure, easily distinguishable normally seeing. Persons with frustration of C. h. do not distinguish color of these circles from color of circles of a background and therefore cannot distinguish the figured or digital images shown them (tsvetn. the tab., Art. 432, fig. 1 — 2). Isikha-ra's tables serve for the same purpose, with their help reveal color-blindness on red and green colors.

Thinner diagnostic method of frustration of C. h. the ano-maloskopiya — a research by means of the special device — the anomalscope is. In the USSR serially released device is the AH-59 anomalscope (fig). For Roubaix

a press for a research C. h.


Anomalosksp of AH-59 has Fig.: 1 and 4 — bar

of a bana for installation of light filters; 2 — an eyepiece; 3 — the regulator of brightness of a field of vision; 5 — the regulator of a color tone of a field of vision; 6 — the electrical power unit.

distribution Nagel's anomalscope.

The principle of operation of the device is based on a trekhkomponentnost of C. h. The essence of a method consists in the equation of color of two-color test fields, from to-rykh one the second is lit in monochromatic yellow color, and, lit red and green, can change color from chistokrasny to purely - green. Inspected shall pick up by optical mixing red and green the yellow color corresponding control (the equation of Re-leya). The person with normal C. h. correctly selects color couple mixing red and green. The person with disturbance of C. h. does not cope with this task. The method of an ano-maloskopiya allows to define a threshold (sharpness) of C. h. separately for red, green, blue color to reveal disturbances of color sight, to diagnose tsvetoanoma-liya.


Extent of disturbance of color sensation is expressed by coefficient of anomaly, to-ry shows a ratio of green and red colors at the equation of the control field of the device with test. At normal trichromats the coefficient of anomaly fluctuates from 0,7 to 1,3, at a protanomaly it makes less than 0,7, at a deuteranomaly — more than 1,3.

The spectral anomalscope of Rabkin allows to investigate color sight in all parts of a visible range. By means of the device definition both the inborn, and acquired disorders of color sight, thresholds of color of distinguishing and degree of functional stability of color sight is possible.

For diagnosis of disturbances of C. h. use also a hundred-hue test of Farnsuort — Menzel. The test is based on bad distinguishing of color by protanopes, deyteranopa and three-tanopami in certain sites of a color circle. From the examinee a number of pieces of a cardboard of different color in the form of a color circle is required to arrange as shades; at disturbance of C. h. pieces of a cardboard are located incorrectly, i.e. not in that order in what they shall follow one after another. The test has high sensitivity and gives information to an o'tipa of disturbance of color sight. Also simplified Farnsuort's test consisting of 15 color test objects is used.

Bibliography: Kravkov S. V. Color

sight, M., 1951, bibliogr.; The multivolume guide to eye diseases, under the editorship of V. N. Arkhangelsky, t. 1, book 1, page 425, M., 1962; Pedkhemch. and the Dream der with D. Perception of light and color, the lane with English, M., 1978; Touch systems, Sight, under the editorship of G. V. Gershuni, etc.,

page 156, JI., 1982; With about to about l about in E. N and And z m and y l about in Ch. A. Color sight, M., 1984, bibliogr.; Adler’s physiology of the eye, ed. by R. A. Moses, p. 545, St Louis a. o., 1981; H u r v i with h L. M. Color vision, Sunderland, 1981; System of ophthalmology, ed. by S. Duke-Elder, v. 4, p. 617, L. * 1968. A. A. Yakovlev-Budnikov.

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