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According to this theory, there are three types of radiant energy receivers (cones) in the eye, which perceive, respectively, the red (long-wavelength), yellow (medium-wavelength) and blue (short-wavelength) parts of the visible spectrum.

All our sensations are nothing more than the result of mixing these three colors in various proportions.

With equally strong stimulation of the three types of cones, a sensation of white color is created, with equal weak stimulation - gray, and in the absence of irritation - black. In this case, the eye perceives the brightness of objects by summing up the sensations received by three types of cones, and color - as the ratio of these sensations.

The three-component theory of color vision is now almost universally accepted. It is assumed that each type of cone contains a corresponding color-sensitive pigment (iodopsin), which has a certain spectral sensitivity (absorption characteristic). The chemical composition of the pigments has not yet been determined.

But, consider the contribution of scientists from different countries to this theory:

Dutch mechanic, physicist, mathematician, astronomer and inventor Christiaan Huygens actively participated in contemporary debates about the nature of light.

In 1678, he published his Treatise on Light, an outline of the wave theory of light. He published another remarkable work in 1690; there he outlined the qualitative theory of reflection, refraction and birefringence in Iceland spar in the same form as it is now presented in physics textbooks.

He formulated the so-called Huygens principle, which makes it possible to study the movement of the wave front, which was later developed by Fresnel and played an important role in the wave theory of light and the theory of diffraction.

The three-part theory of color vision was first expressed in 1756 Mikhail Lomonosov, when he wrote “about the three matters of the bottom of the eye” in his work “On the Origin of Light.”

Based on many years of research and numerous experiments, Lomonosov developed a theory of light, with the help of which he explained the physiological mechanisms of color phenomena. According to Lomonosov, colors are caused by the action of three kinds of ether and three types of color-sensing matter that makes up the bottom of the eye.

The theory of color and color vision, which Lomonosov came up with in 1756, has stood the test of time and taken its rightful place in the history of physical optics.

Scottish physicist , mathematician and astronomer Sir David Brewster made a huge contribution to the development of optics. He is known throughout the world, and not only in scientific circles, as the inventor of the kaleidoscope.

Brewster's optical research is not of a theoretical or mathematical nature; nevertheless, he experimentally discovered an exact mathematical law, behind which his name remains, relating to the phenomena of polarization of light: a ray of light indirectly incident on the surface of a glass plate is partly refracted and partly reflected. A ray reflected at an angle of full polarization makes a right angle with the direction taken by the refracted ray; this condition leads to another, mathematical expression of Brewster's law, namely, the tangent of the angle of total polarization is equal to the refractive index.

He showed that uneven cooling imparted to glass the ability to detect colors in polarized light, a discovery important for the physics of partial forces; Following this, he discovered similar phenomena in many bodies of animal and plant origin.

In 1816, Brewster explained the reason for the formation of colors playing on the surface of mother-of-pearl shells. Before his time, diamond was considered to represent the strongest refraction of light, and ice the weakest in solids; his measurements expanded these limits, showing that lead chromate refracts more strongly than diamond, and fluoride refracts weaker than ice. The phenomenon of light absorption by various bodies, revealed by the fact that many dark lines are found in the spectrum of (solar) light passing through them, was also the subject of Brewster's research. He showed that many of the lines in the solar spectrum come from the absorption of some parts of the light by the earth's atmosphere; studied in detail the absorption of light by nitrous anhydride gas and showed that this substance in liquid form does not form an absorption spectrum. Subsequently, B. discovered that some light lines in the spectra of artificial light sources coincide with the dark, Fraunhofer lines of the solar spectrum, and expressed the opinion that these latter, perhaps, are absorption lines in the solar atmosphere. Comparing the thoughts he expressed on this subject at different times, one can see that Brewster was on the way to the great discovery of spectral analysis; but this honor in any case belongs to Bunsen and Kirchhoff.

Brewster made a lot of use of light-absorbing substances for another purpose, namely, he tried to prove that the number of primary colors in the spectrum is not seven, as Newton thought, but only three: red, blue and yellow ("New analysis of solar light, indicating three primary colors etc." ("Edinb. Transact.", volume XII, 1834). His enormous experimental experience gave him the opportunity to prove this position quite convincingly, but it was soon refuted, especially by Helmholtz's experiments, which irrefutably proved that green color there is undoubtedly a simple one, and that at least five primary colors must be taken.

Optical observations led English physicist, mechanic, physician, astronomer Thomas Young (Thomas Young) to the idea that the corpuscular theory of light that was dominant at that time was incorrect. He spoke in favor of the wave theory. His ideas aroused objections from English scientists; under their influence, Jung abandoned his opinion. However, in his treatise on optics and acoustics, “Experiments and Problems on Sound and Light” (1800), the scientist again came to the wave theory of light and for the first time considered the problem of superposition of waves. A further development of this problem was Jung's discovery of the principle of interference (the term itself was introduced by Jung in 1802).

In Young's paper "The Theory of Light and Colors" given to the Royal Society in 1801 (published 1802), he gave an interference explanation of Newton's rings and described the first experiments in determining the wavelengths of light. In 1803, in his work “Experiments and Calculations Relating to Physical Optics” (published in 1804), he examined the phenomena of diffraction. After the classical studies of O. Fresnel on the interference of polarized light, Young proposed a hypothesis about the transverse nature of light vibrations. He also developed a theory of color vision, based on the assumption that in the retina of the eye there are three kinds of sensory fibers that react to three primary colors.

Scottish by birth, British physicist, mathematician and mechanic James Maxwell in 1854, at the suggestion of the editor, Macmillan began writing a book on optics (it was never completed).

However, Maxwell's main scientific interest at this time was work on color theory. It originates in the work of Isaac Newton, who adhered to the idea of ​​seven primary colors. Maxwell acted as a continuator of the theory of Thomas Young, who put forward the idea of ​​three primary colors and connected them with physiological processes in the human body. Important information was contained in the testimonies of patients with color blindness, or color blindness. In experiments on color mixing, which largely independently repeated the experiments of Hermann Helmholtz, Maxwell used a “color spinning top”, the disk of which was divided into sectors painted in different colors, as well as a “color box”, an optical system he himself developed that made it possible to mix reference colors. Similar devices had been used before, but only Maxwell began to obtain quantitative results with their help and fairly accurately predict the resulting color mixtures. Thus, he demonstrated that mixing blue and yellow colors does not produce green, as was often believed, but a pinkish tint.

Maxwell's experiments showed that white cannot be obtained by mixing blue, red and yellow, as David Brewster and some other scientists believed, and the primary colors are red, green and blue. To represent colors graphically, Maxwell, following Jung, used a triangle, the points inside of which indicate the result of mixing the primary colors located at the vertices of the figure.

Maxwell's serious interest in the problem of electricity allowed him to formulate wave theory of light- one of the theories explaining the nature of light. The main position of the theory is that light has a wave nature, that is, it behaves like an electromagnetic wave (the length of which determines the color of the light we see).

The theory is confirmed by many experiments (in particular, the experiment of T. Young), and this behavior of light (in the form of an electromagnetic wave) is observed in such physical phenomena as dispersion, diffraction and interference of light. However, many other physical phenomena associated with light cannot be explained by the wave theory alone.

In June 1860, at the British Association meeting in Oxford, Maxwell presented his results in color theory, supported by experimental demonstrations using a color box. Later that year, the Royal Society of London awarded him the Rumford Medal for his research in color mixing and optics. 17 May 1861 at a lecture at the Royal Institution ( Royal Institution) on the topic “On the theory of three primary colors,” Maxwell presented another convincing proof of the correctness of his theory - the world’s first color photograph, the idea of ​​which originated with him back in 1855. Together with photographer Thomas Sutton Thomas Sutton) three negatives of color tape were obtained on glass coated with a photographic emulsion (collodion). The negatives were taken through green, red and blue filters (solutions of salts of various metals). By illuminating the negatives through the same filters, it was possible to obtain a color image. As was shown almost a hundred years later by employees of the Kodak company, who recreated the conditions of Maxwell’s experiment, the available photographic materials did not allow demonstrating color photography and, in particular, obtaining red and green images. By a happy coincidence, the image obtained by Maxwell was formed as a result of mixing completely different colors - waves in the blue range and near ultraviolet. However, Maxwell's experiment contained the correct principle for obtaining color photography, which was used many years later when light-sensitive dyes were discovered.

German physicist, physician, physiologist and psychologist Hermann Helmholtz contributes to the recognition of Thomas Jung's theory of three-color vision.

Helmholtz's theory of color perception (Jung-Helmholtz theory of color perception, three-component theory of color perception) is a theory of color perception that assumes the existence in the eye of special elements for the perception of red, green and blue colors. The perception of other colors is determined by the interaction of these elements.

In 1959, the theory was confirmed experimentally by George Wald and Paul Brown of Harvard University and Edward McNichol and William Marks of Johns Hopkins University, who discovered that there are three (and only three) types of cones in the retina that are sensitive to light with a length waves 430, 530 and 560 nm, i.e. to violet, green and yellow-green.

The Young-Helmholtz theory explains color perception only at the level of the cones of the retina and cannot explain all the phenomena of color perception, such as color contrast, color memory, color sequential images, color constancy, etc., as well as some color vision disorders, for example, color agnosia.

In 1868 Leonard Girshman He studied the issues of color perception, the smallest angle of vision, xanthopsia due to santonin poisoning (a disease in which a person sees everything in yellow light) and, under the guidance of Helmholtz, completed his dissertation “Materials on the physiology of color perception.”

In 1870, a German physiologist Ewald Goering formulated the so-called opposing color vision hypothesis, also known as the reverse process theory or Hering's Theory. He relied not only on the existence of five psychological sensations, namely the sensation of red, yellow, green, blue and white, but also on the fact that they seemed to act in opposite pairs, simultaneously complementing and excluding each other. Its essence lies in the fact that some “different” colors form intermediate colors when mixed, for example green and blue, yellow and red. Other pairs of intermediate colors cannot form, but they produce new colors, for example red and green. There is no red-green color, there is yellow.

Instead of postulating three types of cone reactions, as in the Young-Helmholtz theory, Hering postulates three types of opposing pairs of reaction processes for black and white, yellow and blue, and red and green. These reactions occur at the post-receptor stage of the visual mechanism. Hering's theory highlights the psychological aspects of color vision. When the three pairs of reactions go in the direction of dissimilation, warm sensations of white, yellow and red arise; when they proceed assimilatively, they are accompanied by cold sensations of black, blue and light blue. Using four colors in color synthesis gives more possibilities than using three.

Gurevich and Jameson developed Hering's theory of opposing processes in color vision to the extent that the various phenomena of color vision can be quantitatively explained for both an observer with normal color vision and abnormal color vision .

Hering's theory, developed by Gurevich and Jameson, is also known as opponent theory. It retains three receptor systems: red-green, yellow-blue and black-white. It is assumed that each receptor system functions as an antagonistic pair. As in the Young–Helmholtz theory, each of the receptors (or pairs of receptors) is considered to be sensitive to light of different wavelengths, but is most sensitive to certain wavelengths.

The German physicist Hermann Helmholtz made the following assumptions about the work of the eye back in the century before last. Clear and distinct vision of objects at different distances is ensured by changing the curvature of the lens through contraction or relaxation of the ciliary muscle. When you need to see something up close, the ciliary muscle contracts, causing the lens to swell and protrude, allowing the eye to see clearly. And the eye sees into the distance with a relaxed ciliary muscle, while the shape of the eye does not change.

When people are farsighted, the tissues of the lens thicken, i.e., it becomes less elastic, and the person sees well in the distance, but does not see up close. Biconvex glasses enable such people to see up close.

With myopia, according to Helmholtz, the ciliary muscle tenses, so the lens is constantly protruded, and the eye sees perfectly near, but does not see into the distance. Biconcave glasses correct this situation.

Official ophthalmology accepted the assumptions of G. Helmholtz (note - not scientific research, not experiments, but assumptions). Orthodox medicine believes that eye disorders are incurable.

But there is a way of visual retraining and restoration. The pioneers of this effective method were the American ophthalmologist W. Bates and his follower M. Corbet.

W. Bates, a talented and inquisitive man who lived and worked at the end of the century before last and at the beginning of the last century, was not satisfied with traditional methods of treating eyes with glasses, and he tried to find out whether it was possible to return impaired vision to a normal state.

He drew attention to the fact that if a person puts on glasses, his vision will certainly deteriorate, and vice versa, if he goes without glasses for a long time, his vision will always improve.

W. Bates invented a device - the retinoscope, designed for clinical examination of the retina. Using the retinoscope, the eyes of tens of thousands of schoolchildren, hundreds of infants and thousands of animals were examined, including cats, dogs, rabbits, birds, horses, turtles and fish. The device made it possible to take parameters from two meters from the subject’s eyes.

The experimental data completely refuted Helmholtz's assumptions that only the lens is involved in the process of vision, and the shape of the eye does not change.

Experiments have shown that the shape of the eye changes: through contraction of the rectus muscles, the back wall (retina) of the eye approaches the lens when a person looks at a distant object and, conversely, its longitudinal axis becomes longer as a result of contraction of the oblique muscles of the eye when a close object is viewed.

Numerous studies and extensive clinical practice allowed Bates to come to the conclusion that the vast majority of visual disorders are functional and do not arise from pathological changes in the eye itself. The cause of the disorders “is rooted in the habit of using the eyes in a state of increased mental fatigue and physical overstrain.”

Taking this into account, Bates developed an appropriate technique that allows one to relieve both mental and physical eye strain, i.e., eliminate not the symptoms, but the causes of defective vision.

The basis of the Bates method is relaxation. As long as the organs of vision are used under conditions of mental and physical stress, visual impairment will persist and even worsen. The eyes, like no other organ, suffer during mental stress, since in this case the delivery of blood and nervous energy to the eyes is disrupted. It is by no means a fiction that people become blind from rage, that their vision becomes dark from fear, that from grief one can become so numb that one loses the ability to see and hear.

Kepler's idea, like the idea that the change in focus was caused by the elongation of the eyeball, gained many supporters. Some were of the opinion that the ability of the pupil to constrict could be taken into account in explaining this phenomenon, until, after surgery to remove the iris, it was established that the eye accommodated perfectly without this part of the visual mechanism.

Some scientists, dissatisfied with all these theories, rejected all the proposed options and boldly argued that there was no change in focus, this point of view was finally refuted when the ophthalmoscope was invented, which made it possible to observe the eye from the inside.

The idea that a change in focus could be effected by changing the shape of the lens seems to have been first put forward, according to Landolt, by the Jesuit Scheiner (1619). It was later developed by Descartes (1637). But the first concrete evidence to support this theory was presented by Dr. Thomas Young in a publication read before the Royal Society of London in 1800.

“He gave such explanations,” says Donders, “which, properly understood, must be accepted as undeniable evidence.” At the time, however, they attracted little attention.

About half a century later, it happened that Maximilian Langenbeck had the opportunity to seek a solution to this problem using what we know as “Purkinje images.” If a small bright source of light, usually a candle, is held in front of the eye and slightly away from it, then three images are visible: one bright in the normal position; the other is large, but less bright and also in a normal position; and the third is small, bright and upside down. The first comes from the cornea, the transparent covering of the iris and pupil, and the other two come from the lens: the one that stands upright comes from the front of it, and the inverted one comes from the back.

Reflection from the cornea was known in ancient times, although its origin was not discovered until modern times; but the two reflections from the lens were first studied in 1823 by Purkinje, and hence this trio of images now bears his name.

Langenbeck studied these images with the naked eye and came to the conclusion that during accommodation, the image in the middle became smaller than when the eye was at rest. And since the image was reflected from a convex surface, it decreased in direct proportion to the convexity of that surface.

He concluded that the front surface of the lens became more convex as the eye adjusted to near vision. Donders repeated Langenbeck's experiments but was unable to make any satisfactory observations. However, he suggested that if the images were examined with a magnifying glass, they could "show with certainty" whether the shape of the lens changed during accommodation.

Kramer, acting in the direction he proposed, studied images magnified 10-20 times, and this allowed him to verify that the image that was reflected from the front surface of the lens was significantly reduced during accommodation.

Later, Helmholtz, working independently, made a similar observation, but using a different method. Like Donders, he found the image obtained by conventional means on the anterior surface of the lens to be very unsatisfactory and in his Handbook of Physiological Optics he describes it as “usually so indistinct that the shape of the flame cannot be recognized with certainty.”

So, he placed two light sources, or one multiplied by reflection in a mirror, behind a screen in which there were two small rectangular holes. Everything was arranged so that the light from the sources, which shone through the openings of the screen, formed two images on each reflective plane.

During accommodation, as it seemed to Helmholtz, the two images on the front surface of the lens became smaller and closer to each other, while when the eye returned to a state of rest, they increased in size and moved away from each other.

This change, he said, can be seen "easily and clearly." Helmholtz's observations on the accommodative behavior of the lens, published sometime in the middle of the last century, were soon accepted as facts and have since existed as statements in any textbook on the subject.

“We might say,” writes Landolt, “that the discovery of that part of the process of accommodation performed by the crystalline lens is one of the stunning achievements of medical physiology, and the theory of its working is certainly one of the most established, since it not only has a huge amount of clear and mathematical evidence of its correctness, but all other theories put forward to explain accommodation can be easily and completely rejected...

The fact that the eye accommodates near distance by increasing the curvature of its crystalline lens is therefore indisputably confirmed.”

“The issue was resolved,” says Tscherning, “by observing changes in Purkinje images during accommodation, which confirmed that accommodation is caused by an increase in the curvature of the outer surface of the crystalline lens.”

“The greatest thinkers,” says Cohn, “have created many difficulties in the study of this aspect, and only until recently these processes began to be set out clearly and clearly in the works of Sanson, Helmholtz, Brücke, Hensen and Wolkers.”

Huxley refers to Helmholtz's observations as "certain facts to which all explanations of this process must conform," and Donders calls his theory "the true principle of accommodation."

Arlt, who developed the theory of eyeball elongation and believed that nothing else was possible, was initially against the conclusions of Cramer and Helmholtz, but later accepted them.

Studying the various evidence of the theory, we can only be surprised that science allows itself to be based on such an abundance of contradictions in such an important area of ​​medicine as vision treatment. Helmholtz, although convinced of the correctness of his observations showing a change in the shape of the lens during accommodation, still felt unable to speak with certainty about how the supposed change in curvature was accomplished, and it is strange enough that this issue is still discussed .

As he claims, one cannot find " absolutely nothing other than the ciliary muscle to which accommodation could be attributed" Helmholtz concluded that the change in curvature of the lens that he observed must be caused by the activity of this muscle, but he was unable to offer any satisfactory theory of how the muscle acts to achieve such results, and he states unequivocally that the point of view he proposes is purely probabilistic in nature.

Some of his followers, "more loyal than the king himself," as Tscherning described it, " proclaimed as true what he himself explained with great care as probable».

But acceptance in this case was not as unanimous as when it came to observing the behavior of images reflected from the lens.

No one other than the present author, as far as I know, has dared to ask the question whether the ciliary muscle is responsible for accommodation. But, as for how it works, here, as a rule, there is a need to cover this issue in more detail.

Since the lens is not a factor of accommodation, it is not surprising that no one has been able to discover how it changes its curvature. But it is truly strange that these difficulties have in no way shaken the worldwide confidence that the lens is changing.

When the lens is removed due to a cataract, the patient usually has a loss of accommodation and not only has to wear glasses to replace the lost element, but also has to wear stronger reading glasses.

However, few of these cases, after adjusting to the new condition, become able to see at close range without any change in their glasses. The existence of these two classes of cases is a huge stumbling block for ophthalmology. As it turned out, the theory of the lens as a factor in accommodation was widely supported, but the latter was difficult to explain, and at one time, as Dr. Thomas Young noted, there was “great disapproval” of the idea.

Many cases of noticeable change in focus in an eye without a lens have been reported to the Royal Society by competent observers. Dr. Jung, before promoting his theory of accommodation, took the trouble to examine some of them and as a result came to the conclusion that an error had been made in the observation.

However, while he was convinced that in such an eye "the actual focal length remains completely unchanged", he described his own argument in support of this view as only "acceptably convincing". In a later period, Donders conducted several studies, from which he concluded that “in aphakia there remains what is called a barely noticeable trace of the ability to accommodate.”

Helmholtz expressed a similar point of view, and von Graefe, although he saw a “slight remnant” of the ability of accommodation of the eye without a lens, nevertheless decided that this was not essential in order to reject the theory of Cramer and Helmholtz.

“This may be,” as he said, “due to the accommodative action of the iris and perhaps also to elongation of the visual axis by the action of the extrinsic muscles.”

For about three-quarters of a century, the opinions of these specialists have echoed through the literature on ophthalmology. Today it is a widely known and indisputable fact that many people, after removal of the lens due to cataracts, can see perfectly at any distance without changing glasses. Every ophthalmologist I have ever met has seen these types of cases, and many of them are reported in the literature.

In 1872, Professor Forster of Breslau reported a series of twenty-two cases of apparent accommodation in eyes from which the lens had been removed due to cataract. The ages of these people ranged from eleven to seventy-four years, and those who were younger had more power of accommodation than the older people.

A year later, Voinov from Moscow reported eleven cases; ages ranged from twelve to sixty years. In 1869 and 1870, respectively, Loring reported to the New York Ophthalmological Society and the American Ophthalmological Society the case of a young woman of eighteen years of age who, without changing her glasses, was reading the twelve-foot line of a Snellen test card twenty feet away, and was also reading diamond type. from a distance of five to twenty inches. On October 8, 1894, a patient of Dr. Davis, who, as it turned out, could accommodate perfectly without a lens, agreed to introduce himself to the New York Ophthalmological Society.

Dr. Davis reports, “Community members were divided as to how the patient could accommodate near with distance glasses,” but the fact that he could see at that distance without changing his glasses was not discussed.

The patient was a chef, forty-two years old, and on January 27, 1894, Dr. Davis removed a black cataract from his eye, immediately providing him with the usual set of glasses: one to replace the lens, for distance vision, and stronger ones for reading. In October he returned to the doctor. He returned not because there was anything wrong with his eye, but because he was afraid that he might be “straining” his eye.

He stopped using reading glasses after a few weeks and from then on only wore distance glasses. Dr. Davis doubted the veracity of the patient's statements, since he had not seen such cases before, but after research he discovered that the patient's words were similar to the truth. With his eye with the lens removed and a convex glass of eleven and a half diopters, the patient read the ten-foot line on the test card from a distance of twenty feet.

With the same glass, without changing his position, he read small print from a distance of from fourteen to eighteen inches. Dr. Davis subsequently presented this case to the Ophthalmological Society, but received no intelligible response from them. Four months later, on February 4, 1895, the patient continued to read 20/10 at a distance, and the range of distances at which he read near had increased so that he could read "diamond" at a distance of from eight to twenty-two and a half inches.

Dr. Davis ran several tests on him and, although he was unable to find any explanation for his strange behavior, did make some interesting observations. The results of the test on the eye without a lens, by which Donders convinced himself that the eye with the lens missing had no accommodative power, were somewhat different from those presented by the authoritative Dutch doctor, and Dr. Davis therefore concluded that these tests were " completely insufficient to consider this issue controversial.”

During accommodation, the ophthalmometer showed that the curvature of the cornea had changed and that the cornea had moved forward slightly. Under the influence of scopolamine, a drug sometimes used instead of atropine for paralysis of the ciliary muscle (1/10 percent solution every five minutes for thirty-five minutes, then waiting for half an hour), these changes took place as before. They also occurred when the eyelids were held in an upward position.

Thus, Dr. Davis suggested that the possible influence of eyelid pressure and the removed ciliary muscle could explain these changes.

Under the influence of scopolamine, a person's accommodation was also slightly altered, the range of near vision being reduced to only two and a half inches.

Further, the ophthalmometer showed that the patient had no astigmatism at all. He showed the same thing about three months after the operation, but three and a half weeks after it he had four and a half diopters.

In search of more specific explanations for this phenomenon, Dr. Davis conducted similar tests as in the case described in Webster's report in the Archives of Pediatrics. A ten-year-old patient with double congenital cataracts was brought to Dr. Webster. The left lens was covered in frequent punctures, similar to pins; there was only an opaque membrane, the lens capsule, while the right lens was not damaged. Around the edges it was transparent enough that you could at least somehow see.

Dr. Webster made a hole in the membrane that filled the pupil of the left eye, after which the vision of that eye, with glasses replacing the lens, became almost the same as the vision of the right eye without glasses. For this reason, Dr. Webster decided that it was not necessary to prescribe distance glasses to the patient, and prescribed him only reading glasses - flat glass for the right eye and +16 diopters for the left.

On March 14, 1893, he returned and said that he wore reading glasses without taking them off. With these glasses he found that he could read a twenty-foot line on a test card at a distance of twenty feet, and could read diamond type without difficulty at a distance of fourteen inches.

Later, the right lens was removed, after which no accommodation was observed in this eye. Two years later, on March 16, 1895, he was examined by Dr. Davis. He found that the left eye could already accommodate between ten and eighteen inches.

In this case, no corneal changes were observed. The results of Donders' tests were similar to these in the earlier case, and under the influence of scopolamine the eye accommodated as before, but no longer so easily. No accommodation was observed in the right eye.

When compared with accepted theories, these and similar cases cause great confusion. With the help of a retinoscope, an eye without a lens can be seen in the process of its accommodation, but Helmholtz's theory dominates the mind of the ophthalmologist so strongly that he cannot believe even the evidence of an objective test. The obvious fact of accommodation is called impossible, and many theories, very curious and unscientific, have been developed with this in mind.

Davis is of the opinion that “the slight changes in the curvature of the cornea and its slight increase, observed in some cases, may be due to the presence of some accommodative forces, but this is such an insignificant factor that it can be completely neglected, since in some of the the most noticeable cases of accommodation were not observed in aphakic eyes.”

Intentional reproduction of astigmatism is another stumbling block for those who support accepted theories, since it involves changing the shape of the cornea, and such a change is not compatible with the idea of ​​​​an "inextensible" eyeball.

However, it seems that this causes them less concern than the accommodation of an eye with a missing lens, so there are far fewer such cases described. Fortunately, some interesting facts were brought forward by Davis, who studied this phenomenon in connection with the discovery of changes in the shape of the cornea in an eye with a missing lens.

The case occurred with a surgical trainee at the Eye and Ear Hospital in Manhattan, Dr. Johnson. Usually this gentleman had half a diopter of astigmatism in each eye, but he could, by an effort of will, increase it to two diopters in the right eye and one and a half diopters in the left. He did this many times in the presence of many members of the hospital staff and also did this with the upper eyelids held in the upward position, indicating that the pressure of the eyelids had nothing to do with this phenomenon.

Later he went to Louisville, and there Dr. Ray, on the recommendation of Dr. Davis, tested his ability to reproduce astigmatism under the influence of scopolamine (four instillations of a 1/5 percent solution). While the eyes were under the drug, the astigmatism seemed to increase, as measured by the ophthalmometer, to one and a half diopters in the right eye and one dioptre in the left.

From these facts, the influence of the eyelids and the ciliary muscle was excluded, and Dr. Davis concluded that the change in the shape of the cornea was "reproduced almost entirely by the action of the extrinsic muscles." I don’t know what explanation others gave for this phenomenon.

You first need to understand what causes the most common visual impairments, such as myopia and farsightedness. You need to understand how the eye works, how a person sees, and why vision sometimes becomes worse.

This is very important, because only by knowing the structure of the eye and the principle of its operation can one understand what really helps improve vision. By doing this, you will then clearly understand why they are needed, what happens to the eyes, and what the result should be.

At the same time, I want to say that the process of improving vision is not only physics. In restoring your vision, as in any other task you undertake, your inner attitude is important. Imagine yourself as having good vision. Draw in your imagination that you see well, that you see this whole world in all its glory. You need to accept within yourself that you see everything clearly and clearly, that you have one hundred percent vision, and you need to get used to this idea.

When you walk down the street, or walk through the forest, look at the world around you, and don’t go into your thoughts. You need to use your vision, otherwise why do you need to see everything around well? Any organ that is not used will atrophy. You will have to learn to use your vision.

Observe the world around you, try to notice the slightest details, any movement. Observe the appearance of people, birds, cats in your field of vision. Notice how the leaves fall, how the wind sways the branches of the trees.

So, after this short digression, let's return to the eye and look at how it works. The eye can be compared to a camera. The eyeball contains a refractive system with a lens that collects the rays that enter the eye and focuses it on the retina inside the back of the eye. And the optic nerves in the retina collect information and transmit it to the brain.

With myopia, a person sees close objects well. and bad - distant. Cause of myopia When a person sees distant objects poorly, the rays are focused in front of the retina, and not on it.

With farsightedness, a person sees distant objects well, but does not see close ones. Cause of farsightedness when a person does not see close objects well - focusing of rays behind the retina.

Two theories explain why this happens. which are fundamentally different from each other. One of these theories assumes that a person can improve his vision through exercise, while the second denies this possibility.

Let us first consider Helmholtz's theory, which is recognized by official science, but does not imply the possibility of restoring vision without glasses and operations.

Helmholtz theory

In the refractive system of the eye there is a special ciliary muscle that compresses and unclenches lens eyes, and thus changing the refraction of rays.

When a person examines objects close up, the rays come from one center and diverge to the sides, and they have to be refracted more strongly so that they gather again on the retina. At the same time, the lens contracts more strongly.

When a person looks into the distance, the rays fall almost parallel to the eye, and they do not need to be refracted so much. In this case, the lens must become flatter so that the focus is on the retina.

The cause of myopia according to Helmholtz is that the ciliary muscle tenses but cannot relax, and the lens is always in a compressed state. Thus, when a person looks into the distance, the rays are refracted too much, and focusing occurs in front of the retina, and not on it. This is why a person with myopia has trouble seeing distant objects.

Now let's deal with farsightedness. The reason for Helmholtz's hyperopia is that the ciliary muscle is weak and cannot compress the lens properly. Examining distant objects does not require strong refraction of the rays, but when examining near objects, the rays need to be refracted more strongly - but the lens cannot do this. The focus is behind the retina, and focusing simply does not happen. This is why a person with farsightedness has trouble seeing close up.

According to Helmholtz's theory, no amount of exercise will help restore vision. The only thing you can do is wear glasses or contacts, or have surgery. For optometrists and manufacturers of lenses and glasses, the theory is good, as it provides the business with clients who never get better and pay money. But for us. if we want to improve our vision without glasses and operations, another theory is more suitable, which has already proven its relevance and viability by the fact that thousands of people around the world have restored their vision using it. In you will learn about the theory of Bates, who challenged official science and gave many people a chance to restore their vision without the intervention of doctors.

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And then Helmholtz proposed to compensate for farsightedness using a biconvex plus spectacle lens. And the focal length of the system (convex lens plus flat lens) decreases. With the help of glasses, the focus is brought inside the eye, and far-sighted people wearing plus glasses see perfectly close.
And since then, 180 years, all eye doctors in the world have been selecting plus glasses for farsighted people, recommending them for reading and for near work.
Which one of you is farsighted? Raise your hands please.
I also had farsightedness. Well, it would seem that everything is a trap - you can’t escape the glasses. But fortunately for you and me, a wonderful American scientist, professor, ophthalmologist William Bates lived in the world. Bates was a very honest man. After graduating from medical school, he worked as an eye doctor for five years and was horrified and despairing at the results of his work.
Every single patient for whom Bates prescribed glasses, every single one of them, had their vision worsened by the glasses. Not a single patient of his had his glasses restored his vision. And he asked the question: “Well, how can this be?” - he’s an eye doctor, he’s supposed to treat people’s eyes. And he prescribes glasses for them. And their vision from glasses gets worse and worse, and after two, three, four years they come and demand new, thicker and stronger glasses.
And the second thing Bates noticed was that some of his patients went to the countryside, to the mountains, on vacation in the summer. And there they accidentally lost or broke glasses. And he lived back in the nineteenth century, glasses were quite expensive, and people with poor eyesight were forced to go without glasses for a month or two. When they returned from this vacation, they came to him for glasses, he checked their vision using a table and noted with surprise that for many, due to the fact that they went without glasses, the vision of their eyes began to improve.
Bates spent thirty years studying the workings of the human eye. He developed and manufactured a unique device for his time, which he called a “retinoscope.” Using a retinoscope, he could determine the parameters of the eye from a distance of up to two meters. And he watched how the vision changed in the nearsighted, the farsighted, in children during play, in athletes.
And so, after studying the work of the human eye for thirty years, Bates came to the conclusion that Hermann Helmholtz’s theory of vision was completely incorrect. The image in the human eye is not built in the same way as Helmholtz suggested - due to the work of the ciliary muscle and changes in the curvature of the lens, but the image in the human eye is built in exactly the same way as it is built in an ordinary, simple camera. By changing the length of the eye itself. And here the main work in the process of accommodation, that is, focusing the eye, is played by six extraocular muscles.
Each person has six extraocular muscles in each eye. This is the upper longitudinal, which lifts the eye up, this is the lower longitudinal, which lowers the eye down, the internal lateral longitudinal, which brings the eye to the nose, the external lateral longitudinal, which moves the eye to the side, and two very important, so-called transverse muscles of the eye - the upper the transverse one, which fits the eye like this across the top in a semicircle, and the lower transverse one, which fits the eye in a semicircle from the bottom.