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Symptoms of disease - violation of visual perception

Human vision (visual perception) - the process of psycho-physiological processing of the image of objects of the surrounding world, by the visual system.

Which diseases there is violation of visual perception

Symptoms of visual disturbances associated with diseases of the eye.

From the beginning you hold the menu close to the eyes, then remove it at arm's length. All the same words are unclear, and you can't read the name of the dish - whether it is "cake", or "pie".

Approximately at the age of 40 years for the majority of people are beginning to appear causing pain disorders of vision in the form of the ambiguities of visual perception. This is due to the loss with crystals eyes of their elasticity. Eyes lose the ability to focus on close objects. Especially it is difficult to read Newspapers, to distinguish the writing on the card and the other fine print.

In older people, there is a tendency for the development of one of the forms of farsightedness, which is called presbyopia, even in their use of funds for the correction of sight in connection with other disorders. Presbyopia is progressing to about 65 years.

However, this is not the only cause of decline in visual acuity. You can have the vision with the indicator of 20/20, and yet you have a fuzzy perception, if you have to observe the image on the screen of the computer for many hours. Smoke, dust and pollen of plants may cause eye irritation and reduce the severity of view. Visual disturbances also occur because of improper care for contact lenses. Eye irritation may occur in infectious diseases.

The lack of visual perception may be the first symptom of serious diseases such as cataract, glaucoma, degenerative diseases of the retina. Sometimes the vision disturbances have been observed in pathological conditions that are not directly connected with the eyes. To such disorders include diabetes, anemia, abnormal pregnancy, diseases of the kidney and neurological diseases.

Symptoms of visual disturbances associated with psychiatric diseases.

During heavy physical or emotional fatigue is sometimes increased susceptibility to the common external stimuli. Day light suddenly blinded, painting surrounding objects is unusually bright. Sounds stun, slamming the door it sounds like a shot, a clatter of plates becomes unbearable. Odors are perceived badly, causing severe irritation. Touch the body tissue seem to be rough. These changes of perception are called hypertension. The opposite of her condition - hypoesthesia, which is expressed in decrease of susceptibility to external stimuli and is connected with the mental fatigue. The surrounding becomes dim, uncertain, loses sensual concreteness. Things like lose colors, all looks pale and formless. Sounds hear the muffled voices of others lose their intonation. Everything seems to be sedentary, frozen.

Hallucinations are usually called perception, arising without the presence of a real object (vision, ghosts, imaginary sounds, voices, smells, etc.). Hallucinations are, as a rule, a consequence of the fact that the perception is rich not valid external impressions, and inner images. A person who is in the power of hallucinations, they are experienced as a truly perceived, i.e. people during hallucination really see, hear, smell, and do not imagine or represent. For hallucination subjective sensory feelings are the same as valid, as and outgoing from the objective world.

The greatest interest is usually visual hallucinations, characterised by an unusual diversity: visions can be formless (flame, smoke, fog) or, on the contrary, appear to be more clear than the images of real objects. The value of visions is also characterized by large amplitude: there are as thumbnails, so and enlarged, the giant. Visual hallucinations can be and colorless, but much more often they have a natural or extremely intense colouring, usually bright red or blue. Visions can be mobile or stationary, not changing content (stable hallucinations) and constantly changing in the form of a variety of events, played out like on the stage or in the cinema (hallucinations). Arise single images (single hallucinations), part of the subjects, the body (one eye, one half of his face, ear), the crowds of people, flocks of animals, insects, fantastic creatures. The content of the visual hallucinations also has a very strong emotional impact: may frighten, cause terror or, on the contrary, interest, admiration, even admiration.

From hallucinations should be distinguished illusion, i.e. erroneous perception of the real things or phenomena. Obligatory presence of a real object, although the perceived wrongly, is the main feature of illusions, usually shared on the affective, verbal (word) and pareidolia.

Incorrect, distorted the perception of objects and phenomena is called an illusion. Certain kinds of illusions occur in healthy people. However, in contrast to the patients they do not violate the healthy correct in General, identify the subject as a healthy person has sufficient means of checking the correctness of the refinement of his first impressions.

Describes many different illusions, occurring in almost all healthy people. Illusion parallelism arises at the intersection of parallel lines other lines. One of the types of illusions is also a transfer of the properties of the whole figure on its individual parts. Line segment, part of the great figures, seems longer equal to him the line included in the little figure.

Illusions can also be a manifestation of mental disorders. So, the mental illness of a syndrome derealization which is based on a distorted perception of the objects of the surrounding world ("All frozen, glassy", "the World has become like the scenery or the photographic image").

These distortions of perception can be a rather specific in nature and relate to certain signs of objects - shape, size, weight, etc. In these cases say about metamorphopsia. The latter include macropsia, when things seem to be enlarged, macropsia - objects are perceived reduced. When porropsia violated the estimation of the distance: the patient seems to be that the objects are located further than they are in reality.
A kind of illusion in the form of violations of the perception of one's own body ("disorder of the scheme of the body") are observed in the depersonalization syndrome, characterized by distortion of the perception of their own identity ("the Feeling of loss and disassociative I", "Alienation I", etc.).

In violation of the "body scheme" patients experience unique sensations increase or decrease of the whole body and its separate parts: hands, feet, head (the Hands of a very large, thick, Head sharply increased). It is characteristic that the distortion of perception causes the parts of the body often be critically assessed the sick, they understand their painful, false character. To disorders is also a violation of the idea of the ratio of the parts of the body, the position of the body (Ears now placed near - by the nape of her neck, Torso turned by 180 degrees, etc.).

To violations of their perception of their body include some form anosognosia, when the patient does not notice that he had paralyzed limbs, and says it can, at any moment to get out of bed and go. Anosognosia of this type are usually observed in the paralysis of the left limbs, caused by defeat of the right frontal-parietal area of the brain.

The nature of the illusory perception is also polyesthesie - sense multiple angles in a circle of a point on the surface of the skin, which made a shot with the edge of the needles. When synesthesia injection is felt on symmetric parts of the body. So, when shot in the back surface of the right hand sick at the same time feels a shot in the corresponding point of the left hand.

Affective (affect short - term, strong emotional arousal) illusions most often caused by fear or anxious, depressed mood. In this state, even hanging on a coat-rack clothes may seem like a robber, and a random passer - by, a rapist and a murderer.
Verbal illusions are in a false perception of the content of the reality of the conversations around; it seems to a person that these conversations contain allusions to some indiscretions, bullying, hidden threat to his address.

A very interesting and informative pareidolia illusion, usually caused by a reduction of the tone of the mental activity, the General passivity. The usual patterns on the Wallpaper, cracks on the walls or on the ceiling, a variety of light and shade are perceived as a vivid picture, fairy-tale characters, fantastic monsters, unusual plants, colorful panoramas.

Anosognosia called breach of the visual, auditory and kinaesthetic perceptions in the local lesions of the cortex of the brain, caused by vascular diseases, injuries, tumors and other pathological processes. When the subject agnosia at the forefront is the violation of a generalized perception of the objects: patients may not know the image table, chairs, kettle, key and other items, but in that case, when they know the subject, can point and its subsequent relatedness. So, knowing that this person's face, patients may say, know whether this man, remember his name. Recognizing the chairs in a doctor's office, patients with subject agnosia can specify the same type or the other in form and decoration of chairs, which are in the wards, corridors of the clinic.
In some patients, there are visual disturbances, under which the generalized perception of subjects remains relatively intact and at the forefront disorder personal perception. Such patients have difficulty in detecting specific individual items, which they have seen before. Especially brightly these violations are identified in the need to recognize familiar faces. Patients do not know if they had seen this face before or not, a woman's or a man's face in front of them, hardly distinguish facial expressions, do not pick up expressions of joy, fun, laughter, sadness, crying. This form of visual agnosia received the name agnosia on the person, or agnosia personalized features.

One of the forms of violations of visual gnosis has received the name-optical spatial agnosia. In this form of visual agnosia violated the perception of patients spatial arrangement of separate subjects, patients are unable to correctly perceive the spatial relations. Once at the clinic, they can't learn to find the way to the doctor's Cabinet, a dining room, toilet. His chamber they know only by indirect indications number - over the entrance to the chamber or by the characteristic color of the chamber door. These patients also face great difficulties in trying to find his bed in the house. They forget the location of the streets of the city, in which long-lived, can't tell you about the background of his apartment.

The reasons for agnosia
Usually visual agnosia are observed in the defeat of the occipital or partially lower back departments of the parietal lobes of the brain.

The impact of Nizhne-front regions of parietal lobes of the brain are disorders of the higher forms of tactile perception that received the name of astereognosis. Fingering with my eyes closed, any object (key, a coin, a pencil, a pen, brush, etc.)> patients can not determine the form and amount of the subject, learn it. At the same time when the visual perception of patients learn this subject quickly and accurately.

There are also observations from the auditory agnosia, Professor at the defeat of the temporal areas of the brain. In patients with this form of agnosia violated auditory perception. They cannot learn the characteristic noise of the wind, plane, car, sounds different animals, a rustle of paper, etc.
In the basis of agnosia are, apparently, violations of processes of selection of the signal from the noise, the separation of the characteristic features of the objects and comparison of these indicators with those samples, standards, which are stored in the memory of the patients.

Pseudohallucinations

In contrast to the so-called true hallucinations when pseudohallucinations patients are aware of their false character. Hallucinations the image is not in the external environment and directly in the submissions of the patients. To pseudohallucinations experiences can be attributed, in particular, often experienced by patients schizophrenia sound of his own thoughts.

Causes hallucinations and illusions

The mechanism of illusions and hallucinations up to the present time has been studied poorly. The reasons for emerging in illusions and hallucinations violations active, selective nature of perceptions are still not sufficiently clear.

Some illusions, observed in healthy people, can be explained by the so-called installation, i.e. the distortion of perception arising under the influence of the immediately preceding perceptions. This phenomenon is widely studied, a psychologist D.N. Uznadze and his school. Example of the formation of the settings can serve the following experience. The subject is placed in both hands 15-20 times in a row, a big and a small ball of the same weight. Then apply two identical volume of the globe. Some of the subjects estimate is usually one of the balls, like the youngest, the one hand, in which was a small ball. Other subjects found the opposite (a) install and evaluate the same hand which is equal to the volume of the ball, as large.
It is possible that pathology of the machinery installation provides some of the illusion of value objects, observed in the patients. In relation to the pathogenesis of origin hallucinations most likely assumption of their connection with pathological, increased excitability of certain regions in the human brain. In favor of this point of view say, in particular, the experiences of the famous canadian neurosurgeon In. Penfield, called visual and auditory hallucinations electrical stimulation plots of the temporal and occipital lobes of the cortex during operations on the occasion of epilepsy.

Visual disturbances with lesions of the right hemisphere cortex.

In the literature describes a number of features for these defeats syndromes. The most typical of them - optic-spatial agnosia.

The main symptoms of agnosia such:
1) Ignoring the left half of the field of view. In this case, even if the patient is no loss of parts of the field of view (hemianopsia), he does not pay attention to the objects located on the left, or painted on the left side of the picture. Read these patients start with the middle line.
2) Structural apraxia - the inability to copy certain figure, such as a drawing, a failure to draw on their own.
3) Violation of the "topographic memory" - the ability to visually imagine (visualize) a familiar scene, for example the street. Some authors include in this syndrome oculomotor disorder - lack of control of eye movements.

Ignoring the left half of the space is not connected with the defeat of the primary (projection) departments of the visual cortex, so as not binding loss of the field of view (what happens when damaged, the places projection of the crust, where is the projection of the zero point of view). Ignore - this is a functional disorder. At the same time, with lesions of the right hemisphere sometimes noted as if constancy over perception of patients. They have committed some errors, confusing when sensing the letters B and H, could not distinguish between the small circle of the large and etc.

Violation of the ability to assess the spatial arrangement of parts is aggravated by yet another typical syndrome - fragmentation of perception (this is an amazing phenomenon in detail has been investigated by COC. It was connected with the defeat of the right temporal lobe 1). Such patients, for example, instead of a hammer see separate "the cube" or the "square" (the brink of a hammer), see "the man without a head", "butterfly underemployed", see "not finished paint circle" instead of the normal range. These patients do not notice that the figure "missed relevant details, such as the face drawn without his mouth... - image as would be supplemented to a whole".


These same patients with difficulty visually memorize, and then learn specific set images or real objects. At the same time, they are easy to recognize the object as a member of the General category, which has some common characteristics. The specific recognition of objects is difficult, patients do not fix the attention on the specific species or individual differences of the representatives of a wide class.

One of the most typical symptoms of the defeat of the right hemisphere is agnosia on the person - no recognition friends, and even relatives. Such patients will know the face of the person as "a person at all," could not determine whose is this person (even if it was the face of his wife, his son, the treating doctor). These patients were not always able to learn and his face in the mirror. For a given portrait they can't find the party among other portraits. Often, these patients cannot interpret and facial expressions.

Recently received another interesting fact - in a certain localization of lesions (region of the cortex, approximately corresponding to 39 field) patients cease to recognize ordinary objects in the photographs, made by an unusual angle of view (for example, a bucket, photographed from above). Objects in the photographs, made in the usual perspective (for example, the same bucket, photographed from the side), these patients will learn easily. In no other lesions (including symmetric plots the left hemisphere) was not observed.

In a number of cases were also reported violation of color perception. Such patients sometimes "there are only a darker and more bright colors, everything around them seems grey or unusually painted".
Speaking of the right hemisphere, it is appropriate to mention about the results of electric irritation of the temporal lobe cortex, conducted with some of the neurosurgical operations Penfield. In case of irritation, electric shock, these patients have seen vivid visual paintings, reflecting those or other earlier experiences events. The revival of the traces of visual visual memory (visualization) mainly observed in case of irritation right temporal lobe.

We can conclude that the right hemisphere is more than the left, connected with the storage of visual trace. It is not surprising that when lesions of the right hemisphere visual memory increasingly violated, than when lesions of the left.

Visual disturbances with lesions of the left hemisphere of the crust.

The main defect of the perception of these lesions, as it is known, is the aphasia - the inability of the ear to perceive speech and speak. In respect of the visual perception is observed a kind of spatial agnosia - violated the abstract attitude to the spatial relations. "The patient is able to clearly grasp the relationship of the two objects in space, remember the specific situation and even play it... but he is incapable of abstract perceive and reproduce the location of objects, if you want to carry out the "transfer" (for example, to manipulate with the scheme of the subject of relations on paper). The patient are lost, the generalized concepts of spatial relations, he does not understand the meaning of prepositions under, to, from, etc., and is unable to denote the word of the relevant concepts. The patient, in other words, identifies forgetting and the alienation of the meaning of the words denoting spatial relations".
The main defect of recognition in such lesions is Alexis - violation of the reading of the no recognition letters and words (and sometimes characters, for example sweaty characters). The recognition of objects, as a rule, while not violated.

Another defect of these lesions is a violation of "the selected shape of the background", especially in the case of contour, superimposed on each other images of the objects. In General, the relationship aphasia, and impaired ability to distinguish an object from the background specifies the number of authors.

Sometimes when lesions of the left hemisphere also note agnosia depth - the violation of the ability to locate the object in three-dimensional space. These patients cannot determine which of the two objects located closer, in some cases cannot transfer of the objects located on the same line projection (i.e., bad allocate objects on the background of other objects). Only in rare cases, note the link agnosia depth with damage to the right hemisphere.

Visual disturbances with an unclear localization. The most important for the future of such violations is the Balint's syndrome or simultaneous agnosia. Here are a few symptoms, the main of which are:
1) the "spiritual paralysis of the eye" - the patient could not look in a certain direction, but if the subject happens to be in the center of the impaired attention," the sick man sees his one and does not perceive the adjacent object;
2) optical ataxia - the failure to take the subject under the control of view. Usually this syndrome is revealed by bilateral (mainly parietal) lesions.

The basis of this disorder is the inability to see the two objects, even if they are one in the context of another - "patients can't put a point in the center of the circle or the cross, because at the same time perceive or a circle (or cross), or the tip of a pencil, looking at the coccyx pencil, they lose the line, looking at the line, no longer see the tip of a pencil". Some authors emphasize the violation of the perception of depth.

We can suggest that the Balint's syndrome more to do with the defeat of the right hemisphere. Usually the Balint's syndrome note with bilateral lesions of the brain. However, there are bases to believe, that the basic role in the visual defect plays a defeat of the right hemisphere. These reasons are the following.

Firstly, "the paralysis of the eye", probably, is connected with the violation of the regulation of the movement of the eye, and it is celebrated mostly in the lesions of the right hemisphere. Secondly, when you try to take the subject under the supervision of view of the person should assess the specific spatial situation.

Peculiarities of visual perception of patients with separated hemispheres. In the last 15 years to eliminate the epileptic discharges in the brain applied a new method of neurosurgical operations on the full transection all ways, connecting the right and left brain (the corpus callosum, front and rear commissures). This operation led to a significant improvement of the condition of patients. The fact that in patients of the two hemispheres were completely isolated, did not influence significantly on their behavior. However, psychophysical experiments according to the methods described in the previous section (showing the stimulus to the left or right semifield of view), have revealed clear differences in the nature of visual recognition of the right and left hemispheres.

Which doctor should I contact if there is a violation of visual perception

If You have a violation of visual perception, You need to consult with an ophthalmologist, neurologist and psychiatrist.

Are you experiencing violation of visual perception? You want to know more detailed information, or you need an inspection? Please sign up on reception to the doctor! Doctors will examine you, examine the external signs and help to determine the disease the symptoms, they will consult you and provide the necessary assistance. You can also call the doctor on the house.

Do you feel visual perception disrupted? You should be very careful approach to your health in general. People pay not enough attention to the symptoms of the disease and don't realize that these diseases can be critically dangerous. There are many diseases that in the beginning didn't manifest in our body, but in the end it turns out, unfortunately, it have already been treated too late. Every disease has its own specific features typical symptoms - called symptoms of the disease. Definition of symptoms is the first step in the diagnosis of diseases in general. You just need a few times a year to be screened by a doctor, not only to prevent a terrible disease, but also to maintain a healthy spirit in a body and the organism in general.

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Map of the symptoms and the types of disorders is intended solely for educational purposes. We strongly recommend do NOT self-medicate; on all matters relating to the definition of the disease and ways of its treatment, contact your doctor. Md-tips is not responsible for the consequences of use information posted on the site.