The most important organs man's eyes are. The ability to see the world provides central (shaped) and peripheral (peripheral, lateral) vision. The first allows you to recognize the details and shapes of objects. It is divided into near and far. Peripheral vision is a function regulated by a special section of the retina that helps to navigate. With its help, a person distinguishes objects at dusk and at night. Peripheral vision is characterized by the field of view. This is the space perceived by the fixed gaze. Visual impairment is often the first symptom serious pathologies. The deterioration in the perception of objects located on the sides is called hemianopsia. The loss of function, even with the preservation of central vision, makes it clear to a person what it is to lose the ability to navigate in space.
The disease at the initial stages is practically not felt through the features of pathophysiology. Often the disorder is diagnosed during prophylactic medical examination causing shock to the patient. With the progression of the disease, it becomes difficult for a person to read, watch TV, work at a computer, and navigate in space. Eyes begin to hurt more often, vision becomes less sharp, objects "float".
The main causes of pathophysiological changes in peripheral vision are:
- mechanical damage to the retina (against the background of physical, sports loads, stressful situations, head injury);
- glaucoma;
- cataract;
- stroke;
- atherosclerosis;
- vegetative-vascular dystonia;
- benign or malignant neoplasms;
- circulatory disorders;
- hypertension;
- osteochondrosis;
- diabetes;
- degenerative processes in the retina (detachment, thinning);
- vascular disorders;
- age (after 60 years).
After age 60, peripheral vision may deteriorate. This is a natural process.
Normal indicators of the field of view are: 55 ° from the inner and inner upper sides, 90 ° from the outer and outer lower sides, 70 ° from the upper outer, 50 ° from the inner lower, 65 ° from the bottom. Violation of indicators indicates diseases of the brain or eyes.
Reducing the boundaries of the side view to 5-10 ° is diagnosed as a concentric narrowing of the field of view. Without treatment, the disorder progresses to tunnel vision - pathologically limited ability see.
A change in a certain area of the field of view is considered a local loss. Violation is unilateral (homonymous hemianopsia) - loss of left or right zones and bilateral (heteronymous hemianopsia) - loss of opposite areas.
There is a symmetrical and asymmetric impairment of peripheral vision. Symmetrical prolapse of the temporal halves of the visual fields is classified as bitemporal hemianopsia, symmetrical prolapse of the nasal halves - binasal hemianopsia.
There is a loss of only a quarter of the field of view on both sides - homonymous square hemianopia.
scotomas
Scotomas are periodically diagnosed - localized areas devoid of visual function. Violations differ in shape (arc, circle, oval) and location (sectoral, pericentral, central, paracentral, peripheral).
Scotomas are divided into negative and positive. In the first variant, the pathology is not felt by a person and is detected when performing special examinations. In the second case, the violation is described by the patient as a cloudy spot or shadow in the field of vision.
With negative scontoma, a person does not feel deviations in vision.
With absolute scotoma, the ability to see in the affected area completely disappears. If the patient notes that objects become fuzzy, “blurred”, then the pathology is diagnosed as relative.
There is a physiological scotoma. The violation has the form of an oval-shaped blind spot located in the temporal region of the visual field.
With spasm of the arteries of the brain or pinching of the nerve roots, atrial scotomas can occur - reversible loss of local areas of the visual fields. Often disorders are accompanied by nausea, vomiting, pain in the head. With closed and open eyelids, a person is disturbed by flickering along the contour, glare lasting up to half an hour.
Diagnostic methods
Examination helps to clarify hemianopia.
The simplest method for diagnosing narrowing of the visual fields is to compare it in a physician and a patient using the Donders method. The technique is used for serious condition person (paralyzed, bedridden patient), little child, in the absence of medical institution necessary digital devices. To perform the diagnosis, the specialist and the subject must, being at a distance of 1 m, turn to face each other. Everyone covers one eye. The patient looks into the doctor's unclosed eye. And the specialist begins to slowly move the hand or a small table to the center of the field of view. The patient tells the doctor when he sees her.
Various methods are used to diagnose the cause and degree of peripheral vision impairment.
More accurate results are given by perimetry and campimetry. In the first case, the survey is performed using a device called the perimeter. The patient presses his chin to a special stand, closes one eye, and holds the other bright dot at the center of the arc. The object is directed from the sides to the periphery, and the person speaks of its occurrence in the field of view.
Campimetry is performed using a large (2x2) screen. Its surface is illuminated. The person becomes 2 m from the model of the device, closes one eye, and looks through the second through the slit into the center of the dark screen. On it, the specialist moves a small square. The subject reports when he begins to see him. The test is performed several times in different directions.
To diagnose the type and cause of the formation of hemianopia, the doctor may recommend performing CT, carotid angiography, ultrasound of the brain and cervical region spine, MRI, study of hemodynamics of the eye.
Treatment of the disease
For successful treatment pathological changes, it is important to correctly identify and eliminate the factor that provoked its occurrence.
During pregnancy, a deterioration in lateral vision may be a sign of preeclampsia, a condition that is life-threatening for a woman and a child. It is important to normalize the pressure by seeking medical help in a timely manner.
With VVD, visual impairment often occurs against the background of hallucinations, loss of consciousness, loss of strength, headaches, dizziness, fear, and nausea. It is necessary to correct the lifestyle and the help of a psychotherapist.
At malignant neoplasms in the eyes or brain, the patient will need surgery, chemotherapy, radiotherapy.
Treatment depends on the underlying cause of the peripheral vision impairment.
The results of injury age-related changes the retinas are partially or completely corrected by surgery.
With neurological pathologies, they can be prescribed medications(in the form of injections, tablets, drops), restrictive diet (with the exception of caffeinated drinks), vitamin and mineral complexes.
Folk methods of treating the disease will not help to eliminate the disease. Various infusions and decoctions of herbs will only slightly alleviate the condition of a person, alleviating the symptoms of the disease.
There are several computer-assisted techniques that can restore or improve a patient's vision. With the help of execution special exercises and tasks, hemianopsia is partially or completely compensated, which facilitates the orientation of a person in space.
The result largely depends on the physiology of the disease that caused the narrowing of the visual fields, the stage of the diagnosed disorder, the age of the patient, and the characteristics of therapeutic tactics.
Exercises for the development of peripheral vision
To prevent lateral vision disorders, it is important to lead an active lifestyle, control nutrition, avoid stress, and get enough sleep. All these habits increase the resistive capabilities of the organism. You need to stop drinking alcohol and smoking, treat diseases in a timely manner, and regularly check your eyes with an ophthalmologist.
Workout, proper nutrition, an active lifestyle and a lack of stress is a way to avoid problems with peripheral vision.
They train the side view by performing special gymnastics:
- standing near the window opening and selecting an object on the street, it is necessary, without making movements with the pupils, to try to distinguish between objects located on the sides;
- in the center of the page of the book selected for reading, you must draw a vertical line. Trying to look at the strip, you need to try to read the horizontal words printed in the periphery. This exercise perfectly develops the skill of speed reading;
- sit on a chair, lay out images with large symbols on the floor. It is necessary to raise them in turn, allowing them to enter the periphery zone. Gradually, the viewing angle increases. Having mastered the exercise, the person begins training with smaller images;
- you need to select and hold a certain object in front of your eyes. Without looking away, you need to remember another subject. Then add a new one. So you need to fix 7-9 objects. Exercise contributes to the rapid development of peripheral vision.
Light eyelid massage thumbs hands for a minute, the rotation of the eyeballs to the left and right, frequent blinking help to improve microcirculation.
A developed side view is important for representatives of many professions: drivers, seamstresses, athletes, military.
Normal peripheral vision allows you to lead a full life. When the first symptoms of the disorder appear, it is necessary to consult a specialist, undergo comprehensive examination and start treating the cause of the disease. Prompt treatment can help prevent serious complications and deterioration in the quality of life.
Oct 25, 2017 Anastasia Tabalina
Visual fields in the field of ophthalmology are an important concept in diagnostics various diseases. In our article, we will talk about the causes, prevention and methods of treatment of such a pathology as loss of visual fields.
Brief description of the pathology
The field of view is the extent of the surrounding space when looking forward. A change in it is a symptom that indicates the presence of some kind of disease.
Loss of visual fields along with their narrowing is the main pathological symptom in the field of ophthalmology. Each patient who suffers from such a pathology experiences certain characteristic sensations in visual perception. Most accurately, this pathology is detected only with the help of hardware diagnostics using ophthalmic instruments.
Causes of the disease
There are many reasons that can cause visual field loss. They concern not only the organs of vision, but also serve as a consequence of a serious disorder in the brain. The most common causes of visual field disorders include cataracts along with glaucoma, pathology optic nerve, eye injuries, retinal detachment, neurological diseases, high blood pressure, atherosclerosis and diabetes.
In the event that some part of the image is observed, as if through a translucent curtain, then we are most likely talking about a cataract. At the initial stage of glaucoma, the center of vision is usually affected, and only then the pathology can affect the peripheral regions. The reasons for the loss of visual fields should be identified by the doctor.
Complete loss of vision
With severe pathologies of the optic nerve, the eyes completely stop seeing. Eye injuries can lead to loss of certain areas in the field of view, and at the same time to a severe limitation of vision. With retinal detachment, patients tend to see familiar objects in a distorted way. Proportions often change, and straight lines can be curved. Sometimes the patient may feel that he is looking through a veil of fog.
Against this background, the surrounding panorama can be noticeably deformed. Extremely dangerous to the eyes are high pressure along with atherosclerosis. Such diseases cause the appearance of blood clots in the eye vessels. In this case, some part of the retina stops working and the patient has a dark spot in the field of view or a narrowing of the visible area is observed.
Such a phenomenon usually occurs spontaneously and disappears after a while, since the thrombus is destroyed on its own. Loss of visual field is systematic. Small blood clots block the supply of blood to the retina and for a while, the affected area ceases to deliver signals to the brain. Then the blood supply is restored, after which the patient sees well again. There may be a loss of visual field of one eye, or maybe two at once.
Development of hemianopsia
Hemianopsia is a condition when there is a unilateral and versatile loss of part of the visual fields. At the same time, the patient develops blindness in one of the halves of the visual picture. Such a prolapse indicates a pathology nervous system and not about the disease from ophthalmology.
This disease can be temporary or permanent. It all depends on the damage to the parts of the brain. According to the classification, hemianopia is divided into homonymous, heteronymous, bitemporal and binasal.
What does the loss of half of the field of view mean?
Homonymous hemianopsia means the presence of pathological processes in which the patient sees only one half of the visual picture. The reason for the appearance of such hemianopsia is a lesion in a specific place of the visual tract or in the cerebral cortex. According to the classification, such hemianopsia is divided into the following types:
Reasons for the development of hemianopsia
Hemianopia is either congenital or acquired. Most common causes loss of visual fields are:
- The presence of vascular lesions of the brain in the form of hemorrhagic or ischemic strokes.
- development of brain injury.
- Presence brain tumors having any course (it does not matter whether it is benign or malignant).
- The presence of transient or transient circulatory disorders of the brain.
- The presence of hysterical reactions, hydrocephalus, migraine and epileptic seizures.
Hemianopia may be transient with transient vascular disorder or on the background of a migraine. The nature of such a transient disease is explained by short-term swelling of certain areas of the brain. In the event that the edema of this region of the nervous system subsides, then blindness regresses and restoration of visual function is achieved. The appearance of such a symptom in a neurological disease as hemianopsia makes it possible to diagnose and clearly establish the area of brain damage.
Other types: heteronymous, bitemporal and binasal hemianopsia
With heteronymous hemianopsia, nasal or temporal visual fields fall out. The boundary between the displayed and lost parts of the fields runs horizontally. Such hemianopsia, according to the nature of the loss of lateral visual fields, is also divided into partial, complete or square scotoma.
With the bitemporal type (this is the most common type of pathology), there is a loss of the temporal half of the visual field synchronously in both eyes. Such a disease can develop in the presence of basal arachnoiditis or aortic aneurysm. Brain damage is observed in this case in the region of the pituitary gland or in the areas of the optic nerves.
With the binasal type, the nasal half of the visible field is lost on both sides. This type of hemianopia is extremely rare and is usually diagnosed with chiasmatic arachnoiditis, as well as developing hydrocephalus and in the presence of tumor process in the brain.
Carrying out diagnostics
Diagnosis of such a disease is carried out taking into account the study of visual fields using the application clinical symptoms diseases are usually confirmed by additional laboratory tests.
Often, the symptoms of hemianopia indicate the presence of a serious brain lesion. In order to clarify the diagnosis, computed tomography, as well as magnetic resonance imaging and x-ray of the skull. How is visual field loss treated?
Methods of treatment
Treatment of hemianopsia is aimed at eliminating the underlying causes of the disease. The sooner they start healing procedures to eliminate the underlying disease, the more favorable the prognosis may be for later life patient. As a rule, any neurological ailments leave behind persistent organic changes in the central nervous system.
Postponed violation cerebral circulation, head trauma, and prompt removal brain tumors require long-term rehabilitation against the background of residual effects of these diseases. Rehabilitation of patients suffering from the pathology under consideration should be carried out not only with medications.
It is necessary to carry out the adaptation of such patients for orientation in the outside world. Wearing glasses with special mirrors can be of great help in this. Also, classes on specially designed programs that are aimed at improving vision are beneficial.
Forecast
The prognosis for the life of patients with this disease, unfortunately, is unfavorable. Basically this disease organic nature the person remains, but the regression of symptoms does not occur.
A positive prognosis is noted only when a person, after a stroke, which was transferred in the form of a transient circulatory disorder of the brain, leaves his painful state without any consequences. The symptoms of the disorder regress along with the manifestations of hemianopsia. It is this development of symptoms that is observed in migraine, and, moreover, against the background of epileptic seizures and in hysterical reactions. In all such cases, positive dynamics in the disease and a good prognosis for the future are noted.
It is worth mentioning both prevention and what needs to be done to prevent the occurrence of such a disease.
Prevention of pathology
Cast preventive measures risk mitigation eye diseases people should be advised to follow labor regime and rest. This is especially true for those people who constantly work on a computer, as well as in hazardous industries. Persons with the presence high blood pressure, exactly, like diabetics, you need to constantly monitor the slightest negative deviations in your health.
In order for the risks of developing the disease in question to be minimal, it is necessary to carefully monitor the state of health and in no case allow injuries to the head and neck. Among other things, it is necessary to be attentive to the state of health of the heart and blood vessels, and at the same time to conduct a systematic examination by a cardiologist.
In case of discovery unpleasant symptoms, loss of visual fields of any nature, the patient should immediately and without delay consult a doctor. This will certainly ensure the timely determination and diagnosis, which means that it will be started on time. necessary treatment. This will make it possible to eliminate the health problem at the beginning, and at the same time prevent the development of a possible complication.
There is a loss of visual fields as a result of exposure to a person various factors or diseases that damage nerve fibers or light-sensitive cells in the retina. At the same time, local dark spots and a concentric decrease in the area of normal vision are distinguished. If the violations are minor, then the patient does not make any complaints, and the disease is detected by chance.
The disease is more common in women.
Causes of pathology
The impact on the human body of such factors can provoke the loss of the visual field:
- hemorrhages in the nervous tissue;
- prolonged oxygen starvation neurons;
- head injury;
- transient disorders of the blood supply to the brain;
- neoplasms;
- hereditary predisposition;
- hydrocephalus;
- swelling of the brain;
- migraine;
- epileptic seizures;
- hysteria;
- glaucoma;
- atrophy of the optic nerve;
- chromosomal abnormalities;
- neurodegenerative disorders;
- multiple sclerosis;
- hypertonic disease;
- pituitary adenoma;
- atherosclerosis.
Diseases that cause this process
Decreased peripheral vision may signal the development of glaucoma.
Narrowing or loss of visual fields is associated with the development of such ophthalmic diseases in a patient:
- Glaucoma. With this pathology, there is a gradual loss of peripheral vision, most often bilateral. At the same time, there is a significant increase intraocular pressure. Pathology is caused by ischemia of nerve fibers by swollen tissues eyeball. Over time, glaucoma leads to complete loss of vision in both eyes.
- Hemianopia. There is a decrease in the visual field by a quarter or half of the size on the inside or outside of the eye. An important point is the symmetry of the lesion of the right and left eyeball. The disease develops due to damage to nerve fibers at the level of the optic chiasm and affects the neurons of both analyzers.
- Scotomas. Characterized by the appearance in the field of view of areas with dark spots against the background of a normal image. The causes of this disease are associated with a malfunction of the light-sensitive cells of the retina.
The impact on the patient of such diseases can cause a narrowing of the field of view of one or both eyes:
- meningitis;
- brain infection;
- tumor of the pituitary gland or other area of the head;
- aneurysm of the carotid artery.
Varieties
Pathology may be neuralgic in nature.
Depending on the features of the vision of the surrounding world, the following types of disease are distinguished:
- concentric narrowing of fields;
- loss of half of the field, which is more often symmetrical;
- local areas of vision loss.
In the first type, the cause of the pathology is mainly a violation of the functional activity of nerve fibers. In this case, the field of vision is significantly narrowed, and peripheral vision is practically absent. When local scotomas are determined, separate asymmetrical areas of central vision fall out. The cause of this pathology is damage to the retina or individual fibers of the optic nerve.
Glaucoma leads to gradual damage to all visual functions, but changes in the visual field are the most informative. AT initial stage when examining the boundaries of the field of view on the Foerster perimeter or projection perimeters with a white object of 5 mm, the boundaries of the field of view, as a rule, are not changed. However, when examining the field of view in low light, a concentric or nasal narrowing of its peripheral boundaries is found in the very initial period of glaucoma.
Loss of visual fields
How is visual field loss determined, and what does this symptom indicate?
The field of view is the space visible to the eye. It is determined with a fixed position of the head and the most fixed gaze directed forward. If you take this position, then the central vision will allow you to clearly see the objects to which the gaze is directed. Objects on the sides, visible with peripheral vision, will be less clear.
Visual field loss diagnosis
A healthy person sees the fingers of the hand laid aside at least 85 degrees. If this angle is smaller, then there is a narrowing of the field of view. And if a person sees with each eye only a part of the space enclosed in an imaginary right angle, then there is a loss of half of the field of view. This is a formidable symptom of a serious disease of the brain or nervous system.
Accurate diagnosis of loss of visual fields occurs when the patient is examined by a doctor. modern medicine has well-developed methods for examining such patients. There can be many reasons for this phenomenon:
- Stroke, or bleeding in the brain
- brain tumors,
- · inflammatory diseases brain tissue,
- damage to the optic nerve
- Vascular aneurysms and their deep sclerosis.
Local loss of half or quarters of the visual fields is called hemianopsia. It is bilateral, that is, the fields of both eyes fall out. There is also a concentric type of prolapse, reaching to tube vision, when the gaze fixes almost one point. Such a symptom may accompany optic nerve atrophy, the last stages of glaucoma.
But it can also be a temporary phenomenon associated with psychopathic conditions.
Focal loss of visual fields is called scotoma. It is accompanied by the formation of islands, which are perceived as shadows or spots. It happens that the patient does not notice the scotoma, and it is found only during the examination. The loss of a site in the very center of the field of view indicates macular degeneration, an age-related degenerative lesion of the macula (macula) of the retina.
Medicine is making significant progress in the treatment of many of the diseases mentioned. Therefore, patients must comply with all measures prescribed by the doctor. This is the key to successful treatment.
Is it possible to diagnose glaucoma in time? Is this disease curable? Who is at risk?
How fast is it progressing glaucoma ?
Often people do not go to the optometrist for a long time and in most cases the disease is diagnosed at a late stage, when it is impossible to change something. The course of glaucoma is asymptomatic. First, a person loses sight in one eye and often does not pay attention to it. At open angle glaucoma(diagnosed in 85% of cases) the patient does not feel pain, vision is not clouded. When he starts to see worse, he thinks that it is - cataract. and waits for it to mature.
Now all diseases are getting younger. And only glaucoma "mows down" the elderly...
Before glaucoma was diagnosed at the age of 60-70 years. But now there are more patients who are 40-50 years old. Are you over 40? Must annually undergo tonometry - to determine intraocular pressure. This is the only way to detect the disease in time.
And age, and genetic predisposition, and stress, and dietary habits, and cardiovascular diseases… If a glaucoma one of the parents, grandfather or grandmother was sick, be on the lookout: the disease can be inherited. Just like diabetes, the mechanism is the same.
Should the body give some signals that something is wrong with the eyes?
The pathogenesis of this disease is very complex. The intraocular fluid circulates in the middle of the eye. When her pressure rises glaucoma develops. Because the nerve cells very sensitive, they react sharply to "harassment" and can no longer function as it should be normal. it leads to blindness. One of characteristic features glaucoma- loss of fragments from the field of view, starting from the corners of the eyes (the area that is visible at the nose) and ending outside(at the temples). An important point in early diagnosis is the computer determination of the field of view, therefore, it usually does not show us the changes that are in the initial stages. And on the computer we can see all the layers of the retina, measure the thickness and number of nerve fibers. In 15% of cases we diagnose angle-closure glaucoma. The course of this form of the disease is acute, characterized by pronounced pain symptom, which rises and then fades.
Can glaucoma be cured?
Nerve cells do not regenerate. Now this is an axiom. However, science does not stand still. Now there are many drugs that can help such patients. They do not cure glaucoma, but only stabilize the patient's condition - "fix" the sharpness, the field of view.
You need to visit the ophthalmologist regularly measure intraocular pressure. check the field and visual acuity, determine the condition of the optic nerve and retina. If you do this, you won't go blind. By the way, manipulations are performed using the latest technologies. After all, if you measure the intraocular pressure "manually", the figure will not tell us anything. Have only an average approximate parameter. The true pressure of the patient is determined by the thickness of the cornea. It often happens: they checked the intraocular pressure, it is normal. They let the patient go home, and he ... went blind. Many low-pressure glaucoma are now being diagnosed. Previously, the rate was 25-26 mm Hg. pillar. And now the norm is considered to be pressure less than 20 mm Hg. pillar.
What is the best treatment for glaucoma: medical or surgical?
There are three stages: medical, laser and surgical. The best option doctor chooses. if you diagnosed with glaucoma. have no illusions: no diet, no nutritional supplements, no exercise will make your condition easier.
Any treatment for glaucoma begins with medication.
The effect is high. But it often happens that we combine all hypertensive drugs, but there is no desired effect. Or a person admits that she won’t take medicine because she doesn’t have time, forgets, because she has to go on business trips. You can’t do this: I drank for two days, I rest for two days. This is the same as doing nothing. In such cases, it is recommended laser therapy glaucoma. As an option - the usual anti-glaucoma surgery. Surgery does not improve vision. They are made in order to stabilize the function of vision, which is at the time of the operation.
It is important to adhere healthy lifestyle life. Do not smoke, alcoholic drinks use in moderation. Make sure that the menu is dominated by plant foods, more often in the fresh air, move more - walk, swim, ski. Patients should not bend over and stay in the sun for a long time. Therefore, it’s impossible to spend 5-6 hours in the garden! You can not lift weights and make sudden movements.
How about watching TV in a dark room?
We can't even do this. healthy people. In order for our eyes to adequately perceive the image on a computer or TV screen, there must be good lighting. Worked for 45 minutes at the computer, take a break.
Is there any hope for recovery?
Even with advanced stages of glaucoma. when the patient sees almost nothing, and his intraocular pressure “rolls over”, vision can be improved with the help of medications.
Perhaps you will be interested
peripheral vision
peripheral vision is a function of the rod and cone apparatus of the entire optically active retina and is determined by the field of view. The field of view is the space seen by the eyes (eye) that a person sees with a fixed fixed gaze. Peripheral vision helps to navigate in space.
The field of view of each eye has specific parameters. They are determined by the border of the optically active retina and may be limited to the upper edge of the orbit or the bridge of the nose. Normal visual field limits White color the following: outward - 90 °, upward outward - 70 °, upward inward - 55 °, inward - 55 °, downward inward - 50 °, downward - 65 °, downward outward - 90 °. The field of view changes in diseases of the retina, glaucoma, pathology in the visual pathway. These changes consist in concentric or local narrowing of the boundaries and the appearance of dropouts (cattle) in the field of view. In the normal visual field there are physiological scotomas: a blind spot in the temporal half of the visual field at 15° from the point of fixation and angioscotomas. The blind spot contributes to the projection of the optic nerve head, which does not contain foyureceptors. Angioscotomas are located around it. These ribbon-like dropouts in the visual field are associated with large retical vessels that cover the photoreceptor cells.
concentric narrowing of the visual field from all sides it is characteristic of pigmentary dystrophy of the retina and lesions of the optic nerve. The field of view may decrease down to the tube field, when only a 5-10 ° area remains in the center. The patient can still read, but cannot independently navigate in space.
Symmetrical dropouts in the visual fields of the right and left eyes- a symptom indicating the presence of a tumor, hemorrhage, or inflammation at the base of the brain, the pituitary gland, or the optic tracts.
Heteronymous bitemporal hemianopsia- this is a symmetrical half loss of the temporal visual fields of both eyes. It occurs when lesions inside the chiasm of crossing nerve fibers coming from the nasal halves of the retina of the right and left eyes.
Heteronymous binasal symmetrical hemianopsia rare, for example in severe sclerosis carotid arteries, equally squeezing the chiasma on both sides.
Homonymous hemianopia- this is a half-hearted (right- or left-sided) loss of the visual fields and both eyes of the same name. It occurs when there is a pathology affecting one of the visual tracts. If the right visual tract is affected, then left-sided homonymous hemianopia occurs, i.e., the left halves of the visual fields of both eyes fall out. With damage to the left optic tract, right-sided hemianopsia develops.
In the initial stage of a tumor or inflammatory process only part of the optic tract may be compressed. In this case, it is determined symmetrical homonymous square hemianopia. i.e., a quarter of the visual field falls out both in the right and in the left eye. When a brain tumor affects the cortical sections of the visual pathways, the vertical line of homonymous loss of visual fields does not capture the central sections, it bypasses the fixation point, i.e., the projection zone of the macula. This is due to the fact that the fibers from the neurons of the central part of the retina go to both hemispheres of the brain.
Pathological processes in the retina and optic nerve can cause changes in the boundaries of the visual field various shapes. Glaucoma, for example, is characterized by a narrowing of the visual field from the nasal side.
Local dropouts of internal nodes of the field of view, not related to its boundaries, are called scotomas. Scotomas are absolute (complete loss of visual function) and relative (decrease in the perception of an object in the area of the visual field under study). The presence of scotomas indicates focal lesions of the retina and visual pathways. Scotoma can be positive or negative. The patient himself sees a positive scotoma as a dark or gray spot in front of the eye. Such a loss in the field of view occurs with lesions of the retina and optic nerve. The patient himself does not detect a negative scotoma, it is detected during the study. Usually, the presence of such a scotoma indicates damage to the pathways.
Atrial scotomas- these are short-term moving dropouts in the field of view that suddenly appear. Even when the patient closes his eyes, he sees bright, shimmering zigzag lines extending to the periphery. This symptom is a sign of spasm of cerebral vessels. Atrial scotomas may appear at indefinite intervals. When they appear, the patient should immediately take an antispasmodic.
According to the location of the cattle in the field of view, they distinguish
- peripheral,
- central
- and paracentral scotomas.
At a distance of 12-18 ° from the center, a blind spot is located in the temporal half. This is a physiological absolute scotoma. It corresponds to the projection of the optic nerve head. Enlarge the blind spot is important diagnostic value.
Central and paracentral scotomas appear with damage to the papillomacular bundle of the optic nerve, retina and choroid. Central scotoma may be the first manifestation of multiple sclerosis.
Roughly estimate the field of view can be simple and public control method research. With this study, the normal field of view medical worker compared with the field of view of the patient. The patient is seated opposite himself with his back to the light at a distance of 0.5-1 m. The field of view of each eye is examined separately.. To do this, opposite eyes are closed with a palm, for example, the left eye of the patient and the right eye of the researcher, then, on the contrary, the right eye of the patient and the left eye of the medical worker. The patient looks into open eye researcher, who smoothly from the periphery to the center with different parties moves the hand, moving the fingers slightly. The hand is placed in the middle of the distance between the patient and the doctor. The patient must indicate the moment when he notices the appearance of the doctor's hand in the field of view. This method reveals significant narrowing of the boundaries and gross defects in the field of view. This method is considered indicative, since it does not allow obtaining a numerical expression for the degree of narrowing of the boundaries of the field of view. The method can be applied in cases where it is impossible to conduct a study on devices, including in bedridden patients.
Precise determination of the boundaries of the field of view is carried out instrumental methods. These include campimetry- study of the field of view on a concave spherical surface. Campimetry is of limited use; it is used to study the central regions of the visual field within 30-40 ° from the center. The perimeters are in the form of an arc or a hemisphere. The simplest device for studying the visual field is the Foerster perimeter, which is a black 180 ° arc (on a stand), which can be displaced in various directions. The outer surface of the arc is divided into degrees from 0 in the center to 90° at the periphery. For research, white or colored paper objects are used, fixed at the ends of long rods. Paper mugs have different diameters. To determine the outer boundaries of the field of view, a white object with a diameter of 3 mm is used, for measuring defects inside the field of view, a white object with a diameter of 1 mm is used, and colored objects have a diameter of 5 mm.
During the examination, the patient's head is placed on a stand so that the examined eye is in the center of the arc (hemisphere), and the other eye is covered with a bandage. In addition, during the entire study, the subject must fix the mark in the center of the device. It is also obligatory for the patient to adapt to the conditions of the study within 5-10 minutes. The doctor moves along the arc of the Ferster perimeter in various meridians of the study a white or colored mark from the periphery to the center, thus determining the boundaries of their detection, i.e. the boundaries of the field of view.
In projection perimeters on an arc or inner surface hemispherical perimeter (spheroperimeter) a light object is projected. You can use objects of various sizes, brightness and colors. This allows for quantitative (quantitative) perimetry. In this case, two objects of different sizes are used, but the amount of reflected light from them is the same. This technique allows for early diagnosis diseases in which the field of view changes.
The most widespread dynamic (kinetic) perimetry. in which the object moves in space from the periphery to the center along the radii of the circle. Now static perimetry is being introduced more and more widely - the study of the field of view using stationary objects, the size and brightness of which change. Computer controlled automatic static perimeters are used. The researcher chooses a program for presenting test objects to the patient. On a hemispherical or any other screen, white or colored marks move or flash in various meridians. The corresponding sensor fixes the parameters of the subject, denoting the boundaries of the field of view and areas of loss in it on special form or as a computer printout. When determining the boundaries of the field of view for white color, a round mark with a diameter of 3 mm is usually used. If you have low vision, you can increase the brightness of the tag illumination or use a tag with a larger diameter. Perimetry on various colors carried out with a 5 mm mark. Due to the fact that the peripheral part of the visual field is achromatic, the color mark is initially perceived as white or gray of different brightness, and only when entering the chromatic zone of the visual field does it acquire the appropriate color (blue, green, red), and only after that the subject should register a luminous object. The widest borders have a field of view for blue and yellow colors and the narrowest - for green.
The information content of perimetry increases when using marks of different diameters and brightness - the so-called quantitative, or quantitative, perimetry. It allows you to determine the initial changes in glaucoma, degenerative lesions of the retina and other eye diseases. To study the twilight and night (scotopic) field of view, the weakest background brightness and low illumination of the mark are used to evaluate the function of the rod apparatus of the retina.
AT last years practice includes visocontrastoperimetry. which is a method of measuring spatial vision using black and white or color stripes of different spatial frequencies of a different frequency, presented in the form of tables or on a computer display. Violation of the perception of different spatial frequencies (grids) indicates the presence of changes in the corresponding parts of the retina or visual field.
Regardless of the perimeter model in the study of the friction field you must adhere to the following rules :
- the field of view on each eye is examined in turn, the second eye is securely closed with a bandage that does not limit the field of view of the examined eye;
By the nature of the limitation of the visual field, it is possible to determine the localization of the lesion in certain departments visual pathway, stage of glaucoma, degree of degenerative lesion, etc.
The field of view is called the space that the human eye is able to fix in a stationary state. Violation of the visual field is a symptom that cannot be ignored, because it can indicate both eye disorders and the presence of brain pathologies. At the same time, visual field impairment can be local (blocking of visibility in certain parts of the visual field) and global (when the picture that the eye perceives becomes generally narrower).
Visual field impairment: concentric and local narrowing
Violation of the visual field, manifested in the narrowing of its boundaries, is called concentric. If the field of view narrows in some particular area, while the remaining boundaries remain unchanged, there is a narrowing of a local nature.
The degree of visual field impairment can vary, from reduced visibility to a more pronounced narrowing, in which the person seems to be looking through a pipe.
Concentric narrowing of the visual field may occur as a result of disorders of the nervous system (neurasthenia, neurosis, etc.), and may be due to damage to the organs of vision (optic nerve atrophy, glaucoma, etc.).
Visual field disorders can occur in one or both eyes, and can be symmetrical or asymmetrical.
Scotoma - focal impairment of the visual field
Violation of the visual field, which manifests itself in a limited area, the boundaries of which do not coincide with the peripheral boundaries of the visual field, is called scotoma. Simply put, scotomas are spots that occur in any part of the visual field.
Forms of scotomas can be different, and visual field impairment can be relative (when there is a decrease in image clarity within the scotoma) or absolute ( complete absence images in a certain area of the field of view). Also, scotomas are color - when a person cannot see or distinguish certain colors, and flickering (arise as a result of stress, physical and mental stress, circulatory disorders in the optic nerve, some pathologies of the brain).
The main causes and treatment of visual field disorders
The causes of visual field disorders can be different. For example, scotomas or narrowing of the visual field (including tunnel vision) can be caused by:
- cataract;
- glaucoma;
- retinitis;
- eye injuries;
- optic nerve injuries;
- retinitis;
- dystrophic processes;
- retinal detachment;
- atrophy of the optic nerve;
- brain tumors;
- a sharp drop in blood pressure;
- nitrogen poisoning;
- oxygen starvation;
- loss of blood;
- hallucinogens;
- neurological diseases;
- atherosclerosis;
- hypertension;
- diabetes mellitus;
- retinitis pigmentosa.
Since visual field impairment is a symptom, to get rid of it, it is necessary to eliminate the disease or pathology that caused the visual field defect. Therefore, if there is even a slight narrowing of the visual field or loss of parts of the visual field, it is necessary to contact an ophthalmologist and a neurologist. Treatment depends on the cause of visual impairment and may vary from drug therapy before surgical intervention. It is impossible to ignore any violations of the visual field, otherwise it may occur total loss vision (depending on the cause that prompted the violation of the visual field).
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