Sense Organs

SENSE ORGANS provide the central nervous system with signaling about changes occurring in the external environment or within the organism itself, which develops and acts in this environment. At the same time, only a part of the stream of impulses sent by the sense organs is perceived by us in the form of sensations (localized in the cerebral cortex), while the rest of the stream does not reach our consciousness, but plays a very essential physiological role. This signaling on the part of the sense organs constitutes a necessary link in the diverse processes of the central nervous system as an organ of psychic activity up to its highest, specifically human forms. In bourgeois psychophysiology, sense organs are usually considered in mechanistic detachment from the development and activity of the brain, of which they are in fact the instrument (Engels), whereas in turn the activity of the brain necessarily presupposes the functioning of the organism as a whole. On the other hand, bourgeois psychophysiology ignores the question of the deep peculiarity of the sense organs and their role in humans, of the historical-labor basis of their development characteristic of humans with all the consequences flowing therefrom for the anatomy and physiology of the sense organs as concrete historical formations. At best, researchers limit themselves merely to stating the differences between human sense organs and those of animals. Moreover, bourgeois science and the deep crisis it is experiencing (in connection with the crisis of the capitalist system) are characterized by numerous attempts to use the data of the doctrine of sense organs for idealistic assertions about the allegedly fundamental natural limitation of human cognitive abilities, for the "sophisms of idealistic philosophy," consisting in the fact that "sensation is taken not as a connection of consciousness with the higher world, but as a partition, a wall separating consciousness from the higher world" (Lenin). All this requires a radical reworking of the data of the modern doctrine of sense organs on the basis of materialist dialectics, as well as the recognition of their extreme limitations, including in particular the material presented below. Sense organs are usually subdivided into three systems: exteroceptive (external), enteroceptive (internal), and proprioceptive (own). The first includes sense organs located on the periphery: the organs of vision, hearing, smell, taste, and cutaneous senses (pressure, temperature, and pain). The second system encompasses the sensitivity of internal organs. The third system includes the organs of muscle sense, located in muscles, tendons, and joints, and the organs of static sense, which signal the position and movement of the body in space and are located in the labyrinth of the inner ear: in the statocysts, or "auditory vesicles" (utriculus and sacculus) and in the semicircular canals. Sense organs are brought into an active state upon their stimulation from outside or from inside the organism. In this case, each sense organ is characterized by a "specific predisposition" or adaptation to some one definite type of stimulation, which is called an adequate or homologous stimulus of the given organ. The retina is specifically adapted to stimulation by light waves, the auditory organ to sound waves, the organs of smell and taste to chemical stimulations. However, sense organs can also be excited artificially by other stimuli that are not specific to them (inadequate, or heterologous stimuli). For example, the retina can be inadequately excited by pressure or an electric current, which belong to general stimuli for diverse excitable tissues of the organism. An electric current can also inadequately irritate other sense organs: smell, taste, hearing, and cutaneous senses. All sense organs in this case exhibit a remarkable property known under the name of the law of specific energy of sense organs (Johann Müller); it should be mentioned that this prominent physiologist was a representative of "physiological idealism," because, "pointing out, for example, that the sensation of light is obtained with various kinds of action on the eye, he was inclined to deduce from this a denial that our sensations are images of objective reality." Whatever the nature of the stimulus acting on a given sense organ, whether this stimulus is adequate or inadequate, as a result of stimulation there always arises a kind of sensation specific to the given organ. Thus, both upon the action of light on the retina, and upon the passage of an electric current through the eye, and upon pressure on the eyeball, only a visual sensation always arises (examples: the appearance of sparks upon a blow to the eye, flashes of light upon the pulsation of arteries, which are known under the name of the entoptic pulse phenomenon, etc.). The law of specific energy can be applied not only to broad categories of basic kinds of sensations (vision, sight, taste, smell, etc.), but also to narrower, differentiated categories of kinds of sensations, in relation to complex sense organs. Thus, four main types of sensations have been established for the sense of taste: bitter, sweet, salty, and sour. Each of these types of sensations—according to available observations—probably has its own terminal organs or sensitive substance (experiments with isolated stimulation of individual papillae on the tongue and with isolated exclusion of individual types of taste sensations by means of poisons). An analogous assumption is quite likely in relation to types of olfactory sensations as well. The law of specific energy is also very convincingly manifested in relation to cutaneous sensitivity: the skin has separate spatially separated warmth points, cold points, pressure points, and—possibly—pain points. Each of these points, when isolatedly stimulated, regardless of the kind of stimulus, gives only one specific kind of sensation: electrical or mechanical stimulation of the skin at these points gives a sensation of either pressure, or warmth, or cold. The specificity of sense organs is clearly illustrated by a paradoxical experiment: point heating of the skin can cause a sensation of cold if precisely the cold point is subjected to heating. In some cases, it is possible to obtain an analogous paradoxical result of the appearance of a thermal sensation upon cooling the skin. It is very important to emphasize that the specificity of sense organs is manifested not only in relation to the kind of sensation, but also in relation to the degree of excitability of a given organ by various types of stimuli. Excitability in relation to a specific adequate stimulus is much higher than in relation to an inadequate one. Thus, for example, the retina can be excited by an insignificant amount of light energy, equaling only a small number of quanta, whereas for its excitation by various types of inadequate stimuli, the expenditure of much greater energy is required (e.g., electrical or mechanical). The intensity of sensations and reflex reactions arising upon stimulation of sense organs depends on the strength of the stimulus. A very weak stimulus generally remains ineffective: it must not be less than a certain limit, called the threshold of stimulation, in order to evoke some response (sensation or reflex). With a further increase in the strength of the stimulus, an increase in the intensity of sensation occurs, but not continuously, but in leaps: an already existing stimulation must increase by a certain definite finite magnitude, called the difference threshold, to give the first barely noticeable increment of sensation. In this case, the greater the strength of the existing stimulus, the greater the increase of this stimulus is required to cause the first barely perceptible increase in the intensity of sensation. For some sense organs, it was possible to establish a quantitative ratio between the strength of the stimulus and the magnitude of the difference threshold in the form of the so-called psychophysical Weber-Fechner law: the difference thresholds increase in direct proportion to the strength of the existing stimulation, or the ratio between the magnitude of the difference threshold, i.e., the smallest necessary increment in the strength of the stimulation, and the strength of the already acting stimulation always remains constant. This law can be expressed by a simple formula: where I denotes the strength of the stimulation existing at a given moment, ΔI—the difference threshold, i.e., the smallest sensed increment in the strength of stimulation, and K—some constant number characteristic of each organ. The fraction ΔI/I is called the relative difference threshold, and it is different for different sense organs. For example, for vision ΔI/I = 1/100, for muscle sense - 1/30, for skin pressure sense - 1/13 (for skin sense, relative difference thresholds are not identical for different areas of skin). Other formulations of the psychophysical law are also often used: a) with an increase in the intensity of stimulation in a geometric progression, the intensity of sensation increases in an arithmetic progression or b) the intensity of sensation grows in proportion to the logarithms of stimulation according to the formula E = K lg I, where E is the intensity of sensation, I is the intensity of stimulation, K is a constant.

However, this quantitative ratio does not have universal applicability in the physiology of sense organs; for those organs where it is applicable, it is valid only within certain limits: at very weak and very strong stimuli, deviations from the Weber-Fechner law are observed. These deviations for vision can, according to some researchers, be reconciled with the law only by assuming that the constant in the Weber-Fechner formula changes at very low and very high stimulus intensities (Mac Donald, Allen; 1930). For hearing, the Weber-Fechner law is generally inapplicable and must be replaced by another formula (Macdonald, Robertson; 1930). It is very important to clarify the mechanism by which our sense organs distinguish degrees of stimulus intensity. The difficulty of the question lay in the need to reconcile this ability to distinguish the strength of a stimulus with the physiological property of "all-or-none". This property was first discovered in the heart muscle 60 years ago and consists in the fact that the heart muscle, when artificially stimulated, produces a contraction, the intensity of which does not depend on the strength of the stimulus, provided only that this strength of stimulus is not less than a certain value called the "threshold of stimulus"; with a lesser strength of stimulus the heart gives "nothing", and with all other strengths of stimulus it gives "everything". Subsequently, on the basis of a number of studies, this principle was extended to skeletal musculature and nerve trunks: it is assumed that each individual nerve or muscle fiber responds to artificial stimulation according to the "all-or-none" law; the total effect of the whole muscle and the whole nerve trunk depends on the strength of the stimulus only because a stronger artificial stimulus is able to stimulate a larger number of individual fibers. (However, until now the question of the applicability of the "all-or-none" principle to skeletal muscles and nerves is not considered finally resolved.) The application of this principle to sense organs prompted researchers until recent years, when interpreting the Weber-Fechner law and when explaining in general the ability of sense organs to distinguish the strength of a stimulus, to adhere to a similar conception as for skeletal muscle and nerves. It was assumed by the majority of authors that this ability depends exclusively on the fact that a stronger stimulus, for example, brighter illumination of the retina, is able to stimulate a larger number of excitable elements in the sense organs (e.g., rods or cones in the retina or other terminal sensory apparatuses in other organs). New light was shed on this question by a thorough electrophysiological study of sense organs undertaken by Adrian and coworkers over the past 5 years; these works revealed new aspects of the excitation processes taking place in these organs. Adrian studied, using a cathode-ray tube amplifier, the electrical currents arising in sensory nerves upon stimulation of sense organs and accompanying the excitation process. He investigated the isolated eye of a fish (eel), organs of muscle sense (frog), organs of cutaneous sense (cat), and others. It turned out that when a constant stimulus acts on sense organs, excitation arises in them not of a constant character, but of an oscillatory one: the excitation consists of a series of rapidly succeeding individual impulses which propagate further along the nerves to the central nervous system. It is very significant that the oscillatory character of the excitation process in sense organs represents an analogy to the tetanus of skeletal muscle and the rhythmicity of the heart. This analogy with cardiac rhythmicity is further deepened if we note that in relation to sense organs, as well as to the heart, temperature causes a similar effect: an acceleration of rhythm. For example, in one experiment it turned out that for organs of muscle sense the total number of oscillations (impulses) at 15° = 330 per second, and at 5.8° - only 190 per second (at the same stimulus strength). Further, it turned out that the intensity of individual impulses, determined by the intensity of the arising action current, in many cases can be considered independent of the strength of the stimulus. However, with an increase in the stimulus for almost all sense organs (except organs perceiving pain) the frequency of impulses increases, varying within the limits from 5 to 100 (for the frog) and even up to 150 per second (for the cat). Therefore, one can assume on the basis of electrophysiological studies that the ability of sense organs to distinguish the strength of a stimulus in relation to both sensations and reflex reactions is based not only on an arithmetic change in the number of excited elements at different stimulus strengths, but also on a change in the character of the excitation process in each excited element and consequently in each nerve fiber: while this happens, however, only one side of excitation changes - the rhythm of impulses; the other side of excitation - the intensity of each component impulse - remains constant at all stimulus strengths. Thus, Adrian's works refute the idea of "all-or-none" in its simplified, overly schematized application to sense organs and at the same time lay a solid objective foundation for this same idea in a more precise and narrower formulation. Fröhlich (Frohlich, 1913), working on the eye of marine mollusks using an electrophysiological method, arrived even earlier at an analogous result regarding the oscillatory character of excitation in the organ of vision. Fröhlich also showed that with an increase in retinal illumination, the frequency of impulses increases within the range from 40 to 90 per second (for his object). Electrophysiological studies have discovered a number of very essential aspects in the physiology of sense organs. Sense organs possess a refractory phase, i.e., after the generation of a single impulse they pass into a state of short-term in-excitability lasting about 0.01 sec. In this respect, sense organs share the general property of all excitable tissues in general, which also have the property of a refractory phase (heart, skeletal muscles, nerve trunks, and nerve cells). Sense organs possess the property of adaptation: any stimulus causes strong excitation in the first moments, but the intensity of excitation decreases in subsequent moments - the organ "gets used" to the acting stimulus without exhibiting fatigue. This property of "getting used" (adaptation) is well known from subjective psychological observations: thus, for example, sensations of pain, pressure, and smell "blunt" during the action of a constant external stimulus. Adaptation can also be detected for vision through introspection. Light in the first moments of action on an eye that has been in the dark seems dazzlingly bright, and then the sensation of brightness weakens. Under certain experimental conditions - with a well-fixed eyeball - it can be noticed that the illuminated object can disappear completely from the field of vision after approximately 20-30 seconds. This phenomenon of adaptation, which characterizes sensation, is also detected in electrophysiological studies of sense organs; the rhythm of impulses sent by the organ via the sensory nerve to the central nervous system decreases during the action of the stimulus (Adrian, Fröhlich). The capacity for adaptation in different sense organs is expressed to varying degrees. This capacity is manifested to a greater extent for the sense of pain and to the least extent for muscle sense. The remaining organs are arranged in an intermediate series in the same sequence that exists for the corresponding sensations. Consequently, the phenomenon of adaptation in the physiology of sense organs, if not exclusively, then to a significant extent, characterizes processes not in the central nervous system, but at the periphery, in the terminal apparatuses. The electrophysiological technique also sheds light on a number of other very essential features in the physiology of sense organs that were hitherto known only from subjective experience, by the method of introspection, e.g., the phenomenon of after-images, the phenomenon of irradiation for vision, etc. These electrophysiological studies, the beginning of which dates back to the 19th century, lay the foundation for a new branch of physiology: general and special electrophysiology of sense organs. Further development of the doctrine of sense organs must be based on the exceptionally essential proposition of Karl Marx that "the formation of the five senses is the product of world history", and in particular that "the eye has become a human eye just as its object has become a social, human object". Closely connected with these statements is Engels's statement that "with the development of the brain (the main driving factors of this development being labor, and subsequently alongside it articulated speech) went the parallel development of its nearest instruments - the sense organs. As the gradual development of language is invariably accompanied by the refinement of the organ of hearing, precisely so the development of the brain is accompanied by the improvement of all senses in general". The initial factual material for such a development is contained in a number of data of comparative morphology (see

architectonics of the cerebral cortex), pointing—to say nothing of the exceptional differentiation of the human cerebral cortex—to the strong development within it of the peri- and parastriate fields, as well as the fields of the inferior parietal lobe functionally closely connected with them, which serve as the immediate substrate of the complex "gnostic" mechanisms that refine the activity of the sense organs. On the other hand, a large amount of material is provided by neurology and psychopathology, which reveals both the aforementioned "mechanisms" and the active, structural-physiological nature of the activity of the sense organs, which is inextricably linked with phylogenesis and the history of the individual's practical experience (cf. the works of von Weizsäcker, which require a highly critical approach, as indeed do all the sources indicated here). In particularly close connection, the doctrine of sense organs must stand with the development of psychology, which in turn is subject to reconstruction on the basis of Marxist-Leninist theory.

Statistics of diseases of the sense organs. The recording of the incidence of sense organ diseases, according to the international classification of the 1920 revision upon which the statistics given below are built, is carried out mainly by accounting for groups of diseases of the organs of vision and hearing, which in turn are included in the department of nervous diseases. As for disorders of touch and taste, they are not singled out into special groups, but are included directly in the department of nervous diseases, while olfactory disorders are usually accounted for in the department of respiratory organ diseases. All traumatic injuries of the eyes and ears, as well as trachoma and night blindness (hemeralopia), were included in the groups of sense organ diseases, whereas in the newer nomenclature adopted by the USSR State Planning Committee in 1930, eye and ear injuries are separated from sense organ diseases and included in the group of traumatic injuries, trachoma in the group of infectious diseases, and night blindness in the group of diseases due to malnutrition. Gonococcal eye diseases (see Blennorrhea) are classified under infectious diseases in both international and Soviet nomenclature. Mortality. To form an idea of the specific weight of mortality from sense organ diseases compared to mortality from diseases of the nervous system, one can turn to German hospital statistics. Thus, in 1928, in German hospitals, mortality from diseases of the nervous system accounted for 84.9°/₀₀ (pro mille) of total hospital mortality, while mortality from diseases of the auditory organs was 5.6°/₀₀, and from diseases of the visual organs, 0.3°/₀₀. Furthermore, for every 1,000 bedridden patients with infectious eye diseases, from 0.6 to 8.5 died; with other eye diseases, from 1.3 to 1.5; with diseases of the external ear, from 2.5 to 3.9; with diseases of the middle ear, from 18.8 to 21.1; and with diseases of the inner ear, from 22.7 to 28.1 (Table 1). Table 1. Mortality from diseases of the visual and auditory organs in German hospitals for 1925–28 (per 1,000 patients with the respective disease). Diseases 1925 1926 1927 1928. Infectious diseases 8.5 1.4 3.9 19.7 22.7 0.6 1.3 2.5 19.2 28.1 5.9 1.5 2.7 21.1 25.0 1.6. Other eye diseases.... Diseases of the external ear... Diseases of the middle ear... Diseases of the inner ear... 1.3 3.0 18.8 25.8. Detailed data on the incidence of sense organ diseases are available for the city of Moscow for 1926 (census year). Per 1,000 population, it was 106.5 for eye diseases and 35.3 for ear diseases. Of these, conjunctivitis accounts for 38.0, refraction anomalies for 28.5 (including myopia 5.6), foreign bodies in the eye for 4.0, trachoma for 2.8, cataract for 1.7, night blindness for 0.2, and nystagmus for 0.1. Of the diseases of the auditory organs, foreign bodies and deafness account for 0.2 each. According to sex, morbidity is higher in men: for eye diseases it is 122.6, and for women 91.2; for ear diseases, respectively, 38.0 and 32.8. For individual forms, the predominance is observed almost everywhere in men (Table 2). The nature of morbidity by age and sex is illustrated in Tables 3 and 4. The role of profession in the incidence of eye diseases is as follows. Traumatic injuries of the eyes (Table 5) are more common among occupations in the metal industry,

Table 2. Incidence of eye and ear diseases by sex in Moscow in 1926 (per 1,000 population). Diseases, men, women. Conjunctivitis. Trachoma. Myopia. Other refraction anomalies. Foreign bodies in the eye. 40.8 35.2 3.0 2.6 7.0 4.2 27.8 18.2 11.6 1.3. Night blindness. Cataract. Foreign bodies in the ear. 1.5 0.2 0.1 1.9 0.1 0.2. Table 3. Incidence of eye and ear diseases by age and sex in Moscow in 1926 (per 1,000 population). Age, men, women. Age, men. Diseases of the visual organs. Up to 1 yr. 4 yrs. 9 yrs. 14 yrs. 19 yrs. Up to 1 yr. 4 yrs. 9 yrs. 10–14 yrs. 19 yrs. 79.5 86.3 75.5 81.0 58.5 61.8 82.8 86.7 108.0 82.0. 20–29 yrs. 127.3. 30–39 yrs. 112.8. 40–49 yrs. 167.2. 50–59 yrs. 207.0. 60 and older 205.7. 70.4 79.0 134.7 152.7 134.6. Diseases of the auditory organs. 58.6 49.4 59.6 58.7 47.8 50.9 51.2 52.8 41.0 35.0. 20–29 yrs. 36.8. 30–39 yrs. 28.9. 40–49 yrs. 27.3. 50–59 yrs. 24.8. 60 and older 22.4. As for night blindness, living conditions can also be established as having an influence on this disease. Thus, among persons with lower earnings, the rates increase (Table 7—pre-revolutionary data are given). Table 7. Incidence of night blindness and average monthly earnings. Occupations. Machine-building locksmiths. Weavers. Dyers. Day laborers. Average earnings in rubles. Night blindness (per 1,000 workers). 37.87 19.49 16.97 13.46 0.3 11.9 18.0 36.7. Morbidity with loss of working capacity is given in Tables 8 and 9. By individual industries (Table 10), an increased incidence of eye diseases is noted in men in the woodworking and garment industries, and in women, additionally, in the animal products processing industry. Conjunctivitis is higher in men in the garment, textile, and mineral processing industries, and in women in the textile and animal products processing industries. From these comparisons, it is evident that the occupational factor does not manifest itself clearly, possibly

Table 4. Incidence of individual forms of eye and ear diseases by age and sex in Moscow in 1926 (per 1,000 population). Age, conjunctivitis, trachoma, myopia, other refraction anomalies, foreign bodies in the eye, night blindness, cataract, foreign body in the ear (absolute). Men, women, men, women, men, women, men, women, men, women, men, women, men, women, men, women. Up to 1 yr. 60.3 63.7 1.1 0.6 1.0 0.3 0.4 0.5 0.6. 1–4 yrs. 44.6 46.4 1.1 1.1 0.2 0.2 0.2 0.1 0.4 0.4 1.1 0.8 26 43. 5–9 yrs. 28.6 36.6 2.4 2.7 0.5 0.4 1.2 0.8 2.9 3.1 0.9 0.7 24 20. 10–14 yrs. 35.8 39.0 5.4 4.3 1.2 0.4 3.0 4.1 9.1 10.6 2.9 0.9. 15–19 yrs. 35.0 33.3 3.9 1.1 0.5 7.7 5.0 11.6 7.5 17.4 2.2. 20–29 yrs. 44.1 29.2 3.8 2.1 0.7 0.3 12.1 5.9 16.1 8.2 1.9 1.8 78 37. 30–39 yrs. 40.4 32.0 2.8 2.5 0.6 0.4 7.2 4.2 18.4 15.3 16.0 1.5 42 31. 40–49 yrs. 40.9 39.2 2.8 2.9 1.2 1.0 6.8 4.8 74.5 66.0 11.7 1.4 46 16. 50–59 yrs. 37.8 41.8 4.7 3.5 3.9 6.9 4.9 113.2 59.9 5.2 0.9 24 13. 60 yrs. and older 37.1 33.8 4.2 3.2 22.1 19.7 5.5 3.5 67.3 30.1 2.2 0.4 17 16. the rates are especially high among turners and repair locksmiths—20 times greater than among the rural population of the same localities. Table 5. Traumatic eye injuries (workers of Moscow Governorate, men aged 15–59 years, 1911–1915) (ratio per 1,000 workers). Wool-weavers.... 3.5. Cotton weavers... 4.3. Rural population... 5.3. Scutchers....

6.2 Grinders.... 11.6 Stokers..... 14.0 Blacksmiths . . . 29.9 Metal turners 102.1 Repair fitters 112.5 Conjunctivitis among female workers is more common in individuals working in conditions with an elevated content of fine cotton dust in the air and a high temperature. Among scutchers and canvas workers, for example, the rate is 37 times higher than among the rural population (Table 6). Table 6. Conjunctivitis (Moscow Governorate workers - women aged 15-59, 1911-1915) (ratio per 1,000 workers). Driers.... 11.4 Wet-spinners Rural population 30.0 Wool weavers. . . 42.6 Cotton weavers . . . 49.4 Cotton sorters .........50.0 Burlap ironers. . Shearers . . Spinners... Scutchers, canvas workers .... 106.7 64.9 70.8 72.3 78.8 because here there is a combination of detailed professions into entire industrial sectors on the one hand, and on the other hand, a combination within groups of eye and ear diseases of a number of diverse nosological forms. Among individual detailed professions in cotton mills, conjunctivitis, for example, gives more regular gradations of rates (Table 11). Among wet-spinners and slubbers working in the dustiest conditions, the values are highest, while among winders they are lower, and among administrative and technical staff the lowest coefficient is noted. Disability. Of the entire mass of individuals examined at the Moscow Bureau of Medical Expertise (1926), 2.9% were recognized as disabled due to diseases of the organs of vision, and 0.2% due to diseases of the organs of hearing. Thus, in the total mass of causes of disability, the role of diseases of the organs of vision is small, and of the organs of hearing—negligible. Among office workers, the percentage of disabled persons is lower than among workers, both as a result of eye diseases (2.6 and 3.2) and Table. Number of cases of loss of working capacity due to diseases of the sense organs (Moscow and Moscow Governorate, 1925-1928) (per 100 insured persons). Years Eye diseases Including conjunctivitis Ear diseases ... Total number of cases....... 2,042 1,471 1,072 ... Per 100 insured persons 2.5 2.1 1.3 1.0 0.7 0.7 ... Total number of cases . ... Per 100 insured persons 2,881 1,953 1,385 2.6 2.1 1.3 1.0 0.8 0.7 ... Total number of cases . ... Per 100 insured persons 2,767 2,354 1,223 1,185 2.3 2.3 1.0 1.2 0.8 0.7 ... 1928 Total number of cases . ... Per 100 insured persons 2,784 2,049 1,043 848 937 714 2.4 2.1 0.9 0.9 0.8 0.8 of ear diseases (0.2 and 0.4). By production groups, the percentage of disabled persons due to eye diseases is highest among printers (workers) and communications workers (office workers), and due to ear diseases—among metalworkers and medical personnel (Table 12). Table 9. Average duration of a case of loss of working capacity from diseases of the sense organs (Moscow and Moscow Governorate, 1925-1928) (in days). Years Diseases of organs of vision Including conjunctivitis Diseases of organs of hearing For all diseases (excluding childbirth) ... The severity of loss of working capacity due to ear diseases is not as high, while due to eye diseases it exceeds the average (Table 13). Table 10. Indicators largely depend on the increased presence among office workers of individuals with refraction anomalies. Farsightedness among female office workers, for example, makes up about half of all defects noted in the visual apparatus. The effect of age is clearly apparent: farsighted individuals are found more often among the elderly, while for nearsightedness this tendency cannot be detected. Here, the factor of occupational selection is more likely at play: among office workers entering employment (length of service up to ¹/₂ year), the rates are significantly higher than among workers. It is possible that this is the result of previous schooling. Presbyopia among office workers is no more common than among workers. Here, age has the predominant influence (Table 15). Mass screening of professions engaged in production shows that where losses of working capacity in the industry of Moscow in 1928 (per 100 insured persons). Industries Diseases of organs of vision Including conjunctivitis Diseases of organs of hearing ... Woodworking ........... Processing of mineral substances . . . Processing of animal products . . . Pathological morbidity among industrial workers examined in 1925-1928 in Moscow is shown in Table 14. Table 11. Conjunctivitis among cotton workers (1927) (per 100 insured persons) ... Including weavers . . . Winders Other production workers . . Auxiliary workers . . . Junior service personnel . . . Administrative and technical staff . The highest morbidity of the visual apparatus can be observed among office workers, and among women it is higher than among men.

Table 12. Workers ... Office workers Total workers...... Metalworkers....... Printers........ Garment workers...... Textile workers...... Chemists...... Builders ........ Local transport . . . Laborers and day laborers ........ Total office workers .... Technical personnel . Accounting and control personnel ......... Medical and sanitary personnel . Educational workers . Communications workers .... Table 13. Distribution of labor disabled persons by causes and disability groups. Causes of disability Number of examined ... Percentages For all diseases Diseases of organs of vision .... Diseases of organs of hearing .... Percentage distribution by disability groups I II III IV-VI

Table 14. Eye and ear diseases (per 100 examined). Diseases Industrial workers Auxiliary workers Office workers Diseases of organs of vision . . . Diseases of organs of hearing . . .

Table 15. Presbyopia in relation to age (per 100 examined). Age groups Industrial workers Auxiliary workers Office workers 14-19 yrs. 20-39 yrs. 40-59 yrs. Table 16. Conjunctivitis and blepharitis in workers of various industries and professions (per 100 examined). Industry Rubber production . Galosh makers .... Tea packing .... Cotton weavers . . . Paint production . Sausage production . Calico printing factory . Confectionery factory Breweries ... coefficient 4.8%, with 5-8 years of service—5.9%, and with 8 years of service or more—6.3%. Morbidity of the organs of hearing among workers and office workers (1925-1928 survey in Moscow) ranges from 3.1 to 7.4 per 100 examined (Table 17). Table 17. Morbidity of the organs of hearing (per 100 examined). Diseases Industrial workers Auxiliary workers Office workers Diseases of organs of hearing . . . Inflammation of the middle ear Impairment of hearing . . . Production workers have coefficients higher than auxiliary workers and office workers. The main component of the indicators is inflammation of the middle ear.