The study of the state of the pupils and their reactions. Methodology for the study of the organ of vision. Direct response is tested like this

Clinical death can develop for a number of reasons. For example, in case of electric shock, suffocation, poisoning, a number of dangerous pathologies, etc.

It is very important for doctors to know the signs by which one can distinguish loss of consciousness from death.

With proper resuscitation, a person can quickly be brought out of clinical death.

Important! One of the signs of this condition is the lack of reaction from the pupils. They remain enlarged and do not respond to external stimuli.

Structure

Many people think that the hole in the central part of the iris is the pupil. In fact, his constitution is much more complicated. It consists of muscle tissue, which is necessary to ensure the proper supply of light penetrating the iris.

These muscles are called:

sphincter
dilator.

sphincter muscle is located around the opening and is responsible for pupil constriction.

The sphincter is made up of fibers. The thickness of the sphincter is a constant value that ranges from 0.07-0.17 mm. The width of the layer varies from 0.6 to 1.2 mm.

dilator serves to dilate the pupil. It consists of spindle-shaped epithelial tissue with an inner core. The dilator has two muscle layers - anterior and posterior, which are closely intertwined with the iris and pupillary opening.

In diseases of the pupillary reflex, the following diagnostics are performed:

External examination, which reveals the size and asymmetry of the pupils of both eyes.
The direct and friendly response of the pupils to light radiation is assessed.
Checking for components such as convergence and accommodation.

How the human eye is arranged is described in the video:

Reaction to light

Research, which reveal the reaction of the pupil to the flow of light:

direct reaction.
The reaction is called friendly.
convergence and accommodation.

Direct response is tested like this:

A person is seated facing a light source.
One eye is covered with a hand, the other peers into the distance.
Alternate closing and opening of the eyes is carried out, while the doctor observes the reaction of the pupil.
If there are no deviations, then the pupil narrows in the dark, and becomes wider in bright light.

When diagnosing with a friendly response, one eye is darkened, then illuminated. At the same time, the ophthalmologist monitors the reaction of the pupil of the second eye. Normally, it should also expand in the presence of light and narrow in its absence.

And another way - the reaction to convergence and accommodation - involves tracking objects. If any object is close to the eyes, the pupils constrict. The farther the object of observation, the wider the pupils will become.

reference! Sometimes the doctor uses his index finger. The patient looks at its tip, which is either approaching or receding.

Sometimes there is a violation of the reactions of the eye pupil, for example:

due to pathologies of the optic nerve;
nerve responsible for eye movement
with Edie's syndrome.

In addition to the pupil's response to light, its diameters can be changed in the following cases:

With convergence, when the tone of the internal muscles of the eye increases when the pupils are reduced to the nose.
With accommodation, the tone of the ciliary muscle changes when the gaze is transferred from the near to the far distance.

Expansion of the pupillary area can also be observed in such situations:

When frightened, most likely for this reason, the expression “fear has large eyes” arose.
With pain.
During strong emotions or nervous excitement.

The pupil in its volume can also change with the use of certain drugs that affect the proprioreceptors of the eye muscles.

Appearance during the death of brain cells

clinical death the process is called when blood circulation in the body stops, breathing stops and the pulse is not heard. But at the same time, all these processes are reversible, since there are no necrotic changes in the central nervous system and other organs of the human system.

Death of a clinical orientation can last from 3 to 6 minutes, until this time the parts of the brain do not lose their viability to the state of hypoxia. It is necessary to carry out resuscitation as soon as possible, only in this case the person has a chance for life.

Important! With clinical death, the light reaction of the pupils is preserved. But all signs of life in humans are absent.

These circumstances, this is the highest reflex, closing in the area of the cerebral cortex in the brain. From this we can conclude that as long as these large hemispheres are functioning, the pupil will not lose its ability to respond to light.

When biological death occurs, the pupils are also dilated in the first moments. This is due to the convulsive and agonic state of the body.

During clinical death, the openings of the pupils, regardless of the lighting, will be expanded. The skin turns pale, acquires a lifeless shade, the muscles relax, there are no signs of even a slight tone.

Dilated pupils and non-responsiveness to lighting are a sign of brain hypoxia. This condition develops at 40-60 seconds of circulatory arrest and the onset of clinical death.

Other signs

In addition to the fact that the pupils are dilated at the time of clinical death, there are also other distinguishing features of the state:

There is no pulse, and only the carotid or femoral artery can determine that a person is alive. To do this, the ear is applied to the heart, where the heartbeat is heard.
There is a circulatory arrest.
The person completely loses consciousness.
There are no reflexes.
Breathing is extremely weak, it can be seen with a close examination on inhalation or exhalation.
Blueness and pallor of the skin.
The pupils are dilated, there is no reaction to light.

reference! Upon the onset of biological death, the shape of the pupil will be called "cat's eye", that is, within the next 60 minutes after death, with pressure on the eyeball, the pupil takes the form of a narrow slit.

The video describes the signs of the onset of clinical death:

In order to provide maximum assistance to save a person who is in a state of clinical death, it is necessary to do everything necessary for his resuscitation before the arrival of an ambulance, to perform artificial respiration and heart massage.

The eyes are quite an important organ for the normal functioning of the body and a full life. The main function is the perception of light stimuli, due to which the picture appears.

Structural features

This peripheral is located in a special cavity of the skull, which is called the eye socket. From the sides of the eye is surrounded by muscles, with the help of which it is held and moved. The eye consists of several parts:

Directly the eyeball, which has the shape of a ball about 24 mm in size. It consists of the lens and aqueous humor. All this is surrounded by three shells: protein, vascular and mesh, arranged in reverse order. The elements that make up the picture are located on the retina. These elements are receptors that are sensitive to light;
The protective apparatus, which consists of the upper and lower eyelids, the orbit;
adnexal apparatus. The main components are the lacrimal gland and its ducts;
The oculomotor apparatus, which is responsible for the movements of the eyeball and consists of muscles;

Main functions

The main function that vision performs is to distinguish between various physical characteristics of objects, such as brightness, color, shape, size. In combination with the action of other analyzers (hearing, smell, and others), it allows you to adjust the position of the body in space, as well as determine the distance to the object. That is why the prevention of eye diseases should be carried out with enviable regularity.

Presence of a pupillary reflex

With the normal functioning of the organs of vision, with certain external reactions, the so-called pupillary reflexes occur, in which the pupil narrows or expands. The pupillary of which is the anatomical substrate of the reaction of the pupil to light, indicates the health of the eyes and the whole organism as a whole. That is why, in some diseases, the doctor first checks for the presence of this reflex.

What is a reaction?

The pupil reaction or the so-called pupillary reflex (other names are the iris reflex, irritant reflex) is some change in the linear dimensions of the pupil of the eye. Constriction is usually caused by contraction of the muscles of the iris, and the reverse process - relaxation - leads to the expansion of the pupil.

Possible reasons

This reflex is caused by a combination of certain stimuli, the main of which is a change in the level of illumination of the surrounding space. In addition, a change in the size of the pupil can occur for the following reasons:

action of a number of drugs. That is why they are used as a way to diagnose the state of drug overdose or excessive depth of anesthesia;
changing the point of focus of a person's view;
emotional outbursts, both negative and positive equally.

If there is no reaction

Lack of pupil reaction to light may indicate various human conditions that pose a threat to life and require immediate intervention by specialists.

Diagram of the pupillary reflex

The muscles that control the work of the pupil can easily influence its size if they receive a certain stimulus from the outside. This allows you to control the amount of light that enters the eye directly. If the eye is covered from the incoming sunlight, and then opened, then the pupil, which previously expanded in the dark, immediately decreases in size when the light appears. The pupillary arc of which begins on the retina indicates the normal functioning of the organ.

The iris has two types of muscles. One group is circular muscle fibers. They are innervated by parasympathetic fibers of the optic nerve. If these muscles contract, then this process causes Another group is responsible for the expansion of the pupil. It includes radial muscle fibers that are innervated by sympathetic nerves.

The pupillary reflex, the scheme of which is quite typical, occurs in the following order. Light that passes through the layers of the eye and is refracted in them hits the retina directly. The photoreceptors that are located here, in this case, are the beginning of the reflex. In other words, this is where the path of the pupillary reflex begins. The innervation of the parasympathetic nerves affects the work of the sphincter of the eye, and the arc of the pupillary reflex contains it in its composition. The process itself is called the efferent shoulder. The so-called center of the pupillary reflex is also located here, after which various nerves change their direction: some of them go through the legs of the brain and enter the orbit through the upper fissure, others - to the sphincter of the pupil. This is where the path ends. That is, the pupillary reflex closes. The absence of such a reaction may indicate any disturbances in the human body, which is why it is given such great importance.

Pupillary reflex and signs of its defeat

When examining this reflex, several characteristics of the reaction itself are taken into account:

pupil constriction;
the form;
the uniformity of the reaction;
pupillary mobility.

There are several of the most popular pathologies, indicating that the pupillary and accommodative reflexes are impaired, which indicates malfunctions in the body:

Amaurotic immobility of the pupils. This phenomenon is a loss of a direct reaction when illuminating a blind eye and a friendly reaction if vision problems are not observed. The most common causes are various diseases of the retina itself and the visual pathway. If the immobility is unilateral, is a consequence of amaurosis (retinal damage) and is combined with pupil dilation, albeit slight, then there is a possibility of developing anisocoria (pupils become different sizes). With such a violation, other pupillary reactions are not affected in any way. If amaurosis develops on both sides (that is, both eyes are affected at the same time), then the pupils do not react in any way and even when exposed to sunlight remain dilated, that is, the pupillary reflex is completely absent.
Another type of amaurotic immobility of the pupils is hemianopic immobility of the pupil. Perhaps there is a lesion of the visual tract itself, which is accompanied by hemianopsia, that is, blindness of half of the visual field, which is expressed by the absence of a pupillary reflex in both eyes.

Reflex immobility or Robertson's syndrome. It consists in the complete absence of both direct and friendly reaction of the pupils. However, unlike the previous type of lesion, the reaction to convergence (narrowing of the pupils if the gaze is focused on a certain point) and accommodation (changes in the external conditions in which the person is located) is not impaired. This symptom is due to the fact that changes occur in the parasympathetic innervation of the eye in the case when there is damage to the parasympathetic nucleus, its fibers. This syndrome may indicate the presence of a severe stage of syphilis of the nervous system, less often the syndrome reports encephalitis, a brain tumor (namely in the legs), as well as a traumatic brain injury.

The causes may be inflammatory processes in the nucleus, root or trunk of the nerve responsible for eye movements, a focus in the ciliary body, tumors, abscesses of the posterior ciliary nerves.

The shape, size of the pupils and their reaction to light can be used to judge the state of the peripheral part of the visual pathway. The study of the pupils is carried out before the instillation of mydriatics into the eye. It gives important information about the state of the organ of vision and the nervous system, so it should not be replaced by the standard notation "pupils of the correct form, the reaction to light is alive."

Both pupils should be round. The irregular shape of the pupils can be given by scars after ophthalmic surgery, penetrating wounds and rupture of the membranes of the eye, iritis and iridocyclitis. Each pupil is examined separately in low light, while the patient must look into the distance. The difference in pupil diameters is called anisocoria. Anisocoria in the range of 0.5-1 mm is common and in the absence of other abnormalities is not considered a sign of pathology. Directing the light from the flashlight into each pupil, note the speed and degree of its narrowing. As a rule, anisocoria of more than 1 mm or a weak reaction to light in one of the pupils indicate the disease. With the expansion of one pupil, it is necessary to look for other signs of damage to the oculomotor nerve: ptosis, diplopia, paresis of the oculomotor muscles. Even in the absence of these symptoms, sudden dilation of the pupil requires urgent examination, especially if mydriasis is accompanied by headache or other neurological disorders.

Determining the friendly reaction of the pupils to light allows you to identify damage to the visual pathways. The eyes are alternately illuminated with a flashlight (you need to quickly transfer it from one eye to another). Normally, the pupils remain constricted. If, when one of the eyes is illuminated, the pupils dilate, it means that the perception of light by this eye is impaired. When the second eye is illuminated, a friendly constriction of both pupils occurs (due to the decussation of nerve fibers in the midbrain). Such a violation of the direct reaction of the pupil to light with the preservation of the friendly one is called the pupillary symptom of Hun, which, in turn, indicates a relative defect in the afferent pupillary reaction. This reaction should not be confused with the rhythmic contraction and dilation of both pupils, which is normal.

A relative defect in the afferent pupillary response can appear with damage to any structure from the lens to the optic nerve, inclusive. However, more often it is the result of damage to the optic nerve, and cataracts and macular degeneration cause a defect in the afferent pupillary reaction rarely and only in advanced cases. With severe damage to both eyes, the reaction to light of both pupils may disappear, in such cases the pupillary symptom of Hun does not occur.

With Horner's syndrome, the sympathetic innervation of the pupillary dilator and the muscle that lifts the upper eyelid is disturbed. There are ptosis and miosis in the affected eye and anhidrosis of the face on the same side. The pupil is constricted, but reacts to light. It is not always easy to identify anhidrosis, for this you need to check if there are drops of sweat on the red border of the upper lip, examining it through an ophthalmoscope with a lens of +40 diopters. Unilateral mydriasis with delayed, weakened or completely lost direct pupillary response to light in the absence of other pathological signs is called tonic pupillary response (in combination with the absence of tendon reflexes, it constitutes the Holmes-Eidy syndrome).

Sometimes the reaction to accommodation remains relatively intact. Tonic pupillary response is due to degeneration of the ciliary ganglion and postganglionic parasympathetic nerve fibers, which are responsible for pupillary constriction and accommodation. To confirm the diagnosis, a 0.1% solution of pilocarpine is instilled into the eye: in this case, a sharp narrowing of the pupil occurs. Such patients may experience difficulty in reading due to accommodation paralysis, but more often there are no complaints, and mydriasis is detected incidentally. A tonic pupil reaction is also observed with a slight functional disorder of autonomic regulation and occurs in Shy-Drager syndrome, diabetes mellitus and amyloidosis.

Argyle Robertson's sign, the classic sign of tertiary syphilis, is rare. Nowadays, it is more often detected in patients with diabetes mellitus. Argyle Robertson's symptom is also described as a manifestation of meningoradiculitis in Lyme disease. The pupils are usually narrowed, different in size, irregular in shape. They do not react to light, but the reaction to accommodation is preserved. The action of mydriatics is weakened.

Prof. D. Nobel

15-10-2012, 14:25

Description

Pupil size is determined by the balance between the sphincter and the iris dictator, the balance between the sympathetic and parasympathetic nervous systems. The fibers of the sympathetic nervous system innervate the iris dilator. From the sympathetic plexus of the internal carotid artery, fibers enter the orbit through the superior orbital fissure and, as part of the long ciliary arteries, innervate the iris dilator. To a greater extent, the size of the pupil is maintained by the parasympathetic nervous system, which innervates the sphincter of the iris. It is the parasympathetic innervation that maintains the pupillary reaction to light. Efferent pupillary fibers as part of the oculomotor nerve enter the orbit and approach the ciliary ganglion. Postsynaptic parasympathetic fibers in the composition of short ciliary nerves approach the sphincter of the pupil.

Normal pupil size, according to various authors, ranges from 2.5-5.0 mm, 3.5-6.0 mm. It is possible that such fluctuations are due not only to the age of the subjects, but also to the research methodology. Newborns and the elderly tend to have narrower pupils. With myopia, eyes with a light iris have wider pupils. In 25% of cases in the general population, anisocoria is detected - the difference in the diameter of the pupils of one and the other eye; however, the difference in diameter must not exceed 1 mm. Anisocoria greater than 1 mm is regarded as pathological. Since the parasympathetic innervation of the pupils from the Edinger Westphal nucleus is bilateral, the direct and consensual response to light is assessed.

The direct reaction of the pupil to light is on the side of the illuminated eye, the friendly reaction to light is the reaction on the other eye. In addition to the reaction of the pupil to light, the reaction to convergence is evaluated.

RATIONALE

The size of the pupil, its reaction to light and convergence reflect the state of its sympathetic and parasympathetic innervation, the state of the oculomotor nerve and serve as an important indicator of the functional activity of the brain stem, reticular formation.

INDICATIONS

For the diagnosis of a brain tumor, hydrocephalus, traumatic brain injury, brain aneurysm, inflammatory processes of the brain and its membranes, CNS syphilis, trauma and space-occupying formations of the orbit, neck trauma and the consequences of carotid angiography, tumors of the apex of the lung.

METHODOLOGY

It is necessary to assess the state of the pupils in both eyes simultaneously with diffuse lighting, directing the light parallel to the patient's face. In this case, the patient should look into the distance. Such lighting contributes not only to the assessment of the pupil, its diameter, shape, but also to the detection of anisocoria. Pupil size is measured using a pupillometer or millimeter ruler. On average, it is 2.5-4.5 mm. The difference in the size of the pupil of one and the other eye by more than 0.9-1.0 mm is regarded as pathological anisocoria. To study the pupillary reaction to light, which is best done in a dark or darkened room, each eye is illuminated alternately with a light source (flashlight, handheld ophthalmoscope). The speed and amplitude of the direct (on the illuminated eye) and friendly (on the other eye) pupil reaction are determined.

Normally, the direct reaction to light is the same or somewhat more lively than the friendly one. To assess the pupillary reaction to light, four gradations are usually used: lively, satisfactory, sluggish, and no reaction.

In addition to the reaction to light, the reaction of the pupil to the act of convergence is evaluated (or, as they say in foreign literature, at close range). Normally, the pupils constrict when the eyeballs converge to converge.

Giving an assessment of the pupils, pupillary reaction to light and convergence, it is necessary to exclude pathology from the iris and pupillary edge. For this purpose, biomicroscopy of the anterior segment of the eye is shown.

INTERPRETATION

Unilateral mydriasis with areflexia of the pupil to light (a symptom of the clivus edge) is a sign of damage to the oculomotor nerve. In the absence of oculomotor disorders, its pupillomotor fibers are predominantly affected at the level of the brain stem (nerve root) or the nerve stem at the point of its exit from the brain stem. These symptoms may indicate the formation of a hematoma on the side of the lesion or increasing cerebral edema, or be a sign of a brain dislocation of another etiology.

Mydriasis with impaired direct and friendly reaction to light in combination with the restriction or lack of mobility of the eyeball up, down, inside, indicates damage to the root or trunk of the oculomotor nerve (n. oculomotorius - III cranial nerve). Due to the restriction of the mobility of the eyeball inside, paralytic divergent strabismus develops. In addition to oculomotor disorders, partial (half-ptosis) or complete ptosis of the upper eyelid is observed.

Damage to the optic nerve any etiology with the development of visual impairment from a slight decrease in visual acuity to amaurosis can also be the cause of unilateral mydriasis with the manifestation of the Marcus Gunn symptom (afferent pupillary defect). At the same time, anisocoria, in contrast to cases of damage to the oculomotor nerve, is mildly pronounced, mydriasis on the side of the lesion is from slight to moderate. In such cases, it is important to assess not only the direct reaction of the pupil to light on the side of mydriasis, which, depending on the degree of damage to the optic nerve, is reduced from satisfactory to its absence, but also the friendly reaction of the pupil to light both on the side of mydriasis and on the other eye. So, with mydriasis caused by a lesion of the sphincter of the pupil, the direct and friendly reaction of the pupil of the other eye will be preserved, while in a patient with an afferent pupillary defect (Marcus-Gunn symptom), the friendly reaction of the pupil on the side of mydriasis will be preserved if the friendly reaction of the other eye is disturbed. .

Tonic pupil (Adie "s pupil)- a wide pupil in one eye with a sluggish sectoral or almost absent reaction to light and a more intact reaction to convergence. It is believed that the tonic pupil develops as a result of damage to the ciliary ganglion and / or postganglionic parasympathetic fibers.

Adie's syndrome- areflexia of the pupil against the background of its mydriasis. It develops in healthy people, occurs more often in women aged 20-50 years. In 80% of cases, it is unilateral and may be accompanied by complaints of photophobia. The patient sees well both far and near, but the act of accommodation is slow. Over time, the pupil spontaneously contracts and accommodation improves.

Bilateral mydriasis without pupillary reaction to light occurs with damage to both optic nerves and bilateral amaurosis, with bilateral damage to the oculomotor nerves (at the level of the brain stem - damage to the nucleus, root or trunk of the oculomotor nerve at the base of the brain).

Violation of the reaction (direct and friendly) of the pupil to light in both eyes, up to its absence with a normal pupil diameter, it occurs with damage to the pretectal zone, which is observed with hydrocephalus, tumors of the third ventricle, midbrain. Inactivation of the parasympathetic system as a result of, for example, inadequate cerebrovascular perfusion, which is possible due to secondary hypotension due to blood loss, can also lead to bilateral mydriasis.

Unilateral miosis indicates the prevalence of parasympathetic innervation over sympathetic. Usually unilateral miosis comes from Horner's syndrome. In addition to miosis, this syndrome develops ptosis and enophthalmos (as a result of reduced innervation of the Müller muscle) and slight conjunctival irritation. The reaction of the pupil to light practically does not change.

Bilateral miosis, which practically does not expand during the instillation of mydriatics with a sluggish reaction to light and normal to convergence - a manifestation of Argyle Robertson's syndrome, is recognized as pathognomonic for syphilitic lesions of the central nervous system.

Bilateral miosis with preserved reaction to light indicates damage to the brain stem and may be the result of structural or physiological inactivation of the sympathetic pathway descending from the hypothalamus through the reticular formation. In addition, bilateral miosis may suggest metabolic encephalopathy or drug use.

DIFFERENTIAL DIAGNOSIS

Afferent pupillary defect(pupil of Marcus-Gunn) is characterized by unilateral mydriasis, a violation of the direct reaction to light on the side of the lesion and a violation of the consensual reaction to light in the other eye. Mydriasis, as a manifestation of damage to the oculomotor nerve, is usually combined with a violation of the mobility of the eye up, down and inside, as well as varying degrees of semi-ptosis or ptosis of the upper eyelid. The defeat of only the pupillomotor fibers of the oculomotor nerve is manifested by unilateral mydriasis with impaired direct and friendly reaction to light in the affected eye and normal photoreaction in the other eye. With damage to the structures of the midbrain, the violation of the pupillary reaction to light is symmetrical in both eyes. In this case, most often the diameter of the pupils is not changed and the pupillary-constrictive reaction to convergence (light-near dissociation) is preserved.

Tonic pupil(Adie "spupil), in addition to unilateral mydriasis, is characterized by a sluggish sectoral reaction to light (direct and friendly), which is better determined by examination with a slit lamp, and a relatively intact pupillary response to convergence. However, it must be remembered that mydriasis and violation pupillary photoreactions may be due to damage to the sphincter of the pupil and pathology in the iris.

A distinctive feature of unilateral miosis in Horner's syndrome compared with miosis in iritis is the preservation of photoreaction and the combination of miosis with partial ptosis and enophthalmos.

In differential diagnosis, pharmacological tests (for pilocarpine, cocaine) play a certain role.

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