Why are some people's pupils not round? Changes in the shape and size of the pupil

First of all, it should be said that the shape of the pupil is associated with the features of the function of the muscles that provide constriction, expansion of the pupils and nerves that provide the correct movements of the muscles that move the pupil. Therefore, the causes of the difference in the size of the pupils are varied and may be associated with muscle pathology. In addition, this may contribute to violations nervous system and various diseases internal organs.
In the event that the diameter of the pupils is not the same, it is necessary to exclude, first of all, local intraocular causes this symptom, so you need to consult an ophthalmologist. Violation of the size of the pupil may be the result of congenital unequal muscle tone that sets the iris in motion.
There is both dilation and narrowing of the pupils, absence or decrease in the reaction of pupils to light.
Pupil dilation may be associated in young people with an unstable function of the autonomic nervous system, then a neurologist's consultation and an examination for the syndrome are required. vegetative dystonia. In older people, dilated pupils may indicate glaucoma, a serious condition that requires observation and treatment by an eye doctor. The pupil dilates under the influence of atropine or its derivatives, for example, when examined by an ophthalmologist, they are often buried in the eyes special means, which cause pupil dilation and allow you to fully examine the vessels located in the fundus, after this manipulation, one of the pupils may remain dilated for some time. In addition, the pupils or one of the pupils are often dilated in the blind or visually impaired in one eye. Temporary expansion can be caused by inflammatory processes in the chest and in the abdominal cavity.
Constricted pupils usually indicate use drugs including morphine. Also narrow pupils or pupil may be associated with various diseases nervous system, including infectious lesions or circulatory disorders in the brain and spinal cord. A change in the size of the pupils can accompany an attack of a migraine-type headache (headaches that are usually unilateral pulsating in nature, occurring paroxysmal), when an expansion or contraction of the pupil occurs on the side of severe pain.
Noteworthy is the fact that pupillary constriction is accompanied by constriction palpebral fissure and slight drooping of the eyelid in one eye. These symptoms may be caused by pathological changes in the nervous system at the level of transition cervical spinal cord in thoracic region. Disease factors in this case, for example, can be osteophytes - the growth of bone and cartilage tissue due to osteochondrosis or circulatory disorders in the spinal cord. In addition to diseases of the nervous system, the aforementioned symptoms can cause lung diseases, including lung tumors, vasodilation, or aneurysms. Therefore, if there are signs of pupillary constriction, you should undergo an x-ray of the lungs, an examination by a therapist, as well as a neurologist.
The next important sign of ill health is a violation of the normal reaction of the pupils to light. Normally, when moving from a bright room to a dark one, or vice versa, a change in the size of the pupils occurs. When a violation is found correct reaction pupils to light, as well as one- or two-sided narrowing of them, first of all, an infection such as syphilis should be excluded. It seems paradoxical that venereal disease, like syphilis, can manifest itself as a violation of the shape and reaction of the pupils. However, this fact has long been known to doctors, since with this infection, in addition to damage to the genital tract, damage to the nervous system is also observed. In this case, it is necessary to consult a venereologist.
In addition, if the reaction to light is impaired, the pupils or the pupil are dilated, and in addition to this, the person cannot look up - we can talk about one of the types of brain tumor.
So, the reasons for the violation of the shape of the pupils and their reaction to light are different, often serious diseases manifest themselves as this sign, therefore, if you or your relatives and friends have similar symptoms you need to consult your doctor.

O. A. Malysheva, neurologist the highest category, Ph.D. Institute of Clinical Immunology SB RAMS

Vision is the greatest gift of nature, which we begin to fully appreciate only when there is a threat to lose this good. There are many eye diseases and various pathologies that can lead to partial loss of vision or complete blindness. Even today, there are many myths associated with a misunderstanding of the structure and role of the eyes. A striking example is the so-called double pupil. Most people take this name literally, that is, as the presence in the eyes of two separately existing pupils with their own iris and functions. In fact, it is contrary to human nature. When such a complex pathology occurs during prenatal development fetus, it would certainly be associated with other violations of the structure of the body and brain of the child, so he could not be viable.

But some pathologies may well exist in absolutely normal people, however, all of them, one way or another, are associated with visual impairment, because it is clear that the eyes cannot see without pupils. So what is the phenomenon of the pupil, and what violations can actually exist?

Eyes without pupils are completely blind, devoid of functionality, since light does not enter them and, along with it, the image of the surrounding world. The pupil is the opening in the iris of the eye of all vertebrates. This large class of beings also includes us humans.

There are several types of pupils:

The pupils in both eyes work synchronously, letting in a dosed amount of light, this is called a friendly reaction of the pupils to light. When the light flux is weakened, the pupils enlarge, that is, they expand to let in more light. In strong light, the pupils constrict, protecting the eye from being damaged by too much light. Thus, healthy pupils react to light and dilate in the dark. Based on this ability old method diagnosing the state of human health: at very serious injuries, especially in the brain, the pupil does not respond to light or the reaction is inadequate, for example, one pupil dilates and the other does not.

The measurement of pupil size in reaction to light in a presbyopic state is one of the first signs natural aging body and is manifested by the inability to focus on small objects located close to the person.

There are many natural visual impairments associated with the pupil. Persistently circulating rumors about a double pupil require a detailed explanation.

The reality of the existence of a double pupil

A fully double pupil, that is, two separately existing pupils with their own iris, as they are often depicted on the Internet, is in fact a phenomenon invented by a person's rich imagination, as well as eyes without pupils. In reality, eyes without pupils are different types diseases, for example, a thorn covering the eye, or an acquired coloboma. With this disease, the functioning of the sphincter is disrupted and the eye seems to be devoid of a pupil.

Two pupils in one eye can appear if the correct shape of the pupil opening is disturbed and peculiar strands appear in it, which visually divide the pupil into several parts. As a result, it seems to us that the patient's eye has not one, but several pupils, which we see as black dots. different shapes. In this case, the iris of the eye remains still one per eye. This disease is called polycoria, with it there are several holes in the iris and because of this it seems that the dislocation of the pupil is changing.

There are two types of this disease:

• True polycoria. With it, all the pupils in the eye expand and contract under the influence of light.
• Pseudopolycoria, in which only one pupil is "working" and reacts to light.

Summing up, we can say that several pupils can indeed exist, but only within the same iris.

Existing defects in the structure of the pupils

Any change in the shape of the pupil necessarily affects the vision of a person. It is clear that a double pupil will necessarily lead to disturbances in the perception of the environment, therefore, with congenital polycoria at the age of the first year of life, the child is shown to perform surgical operation for elimination cosmetic defect and restoration of vision. Usually, the operation is sent if there are more than 3 pupils and their diameter exceeds 2 mm. In other cases, you can correct the appearance of the eye and help improve vision, remove discomfort with the help of special contact lenses.

It is clear that the eyes without pupils cannot see. This impression is most often created by eyes with a thorn, with cataracts or with coloboma. In most cases, such disorders are treated only by surgery. Very often eye defects that create a false sensation total absence pupil or dividing it into several smaller areas, occurs after a mechanical or chemical damage visual organs, as well as after a number of injuries, especially those associated with penetrating wounds and damage to the eyes during explosions. Sometimes such disorders can occur after an unsuccessful surgical operation.

In many cases, various changes in the structure of the eye and its appearance associated with hereditary genetic diseases or with "failures" that occur during intrauterine formation fetal organs. The eyes are a very delicate structure, and many factors can have a damaging effect on them, for example, diseases, environment, reception of various medications and stressful situations.

An irregularly shaped pupil is very often a sign of a coloboma. This disease is a consequence of disorders in the formation of the eye during pregnancy and does not always lead to severe visual defects, however, due to its congenital nature, it can be accompanied by many other defects in the structure of the body and internal organs. Sometimes with coloboma, vertical pupils appear that dilate and constrict as usual, or it looks like a spot on the iris and it seems to outsiders that the person simply does not have a pupil.

There is also such a placement disorder as ectopic pupil, in which it is not in the center of the iris, but is shifted to the side. This syndrome also means that vision is impaired and correction is required.

Constantly enlarged pupils and the feeling that a trash can is stuck in the pupil indicate the presence of a clear problem.

Any discomfort, especially a change in the shape and size of the pupils, requires a quick visit to an ophthalmologist to identify true reason Problems.

From the moment the child is born, it is necessary to carefully monitor his health, not forgetting to pay attention to the eyes of the baby. Lots of unpleasant diseases can be successfully corrected and cured in the first year of a child's life.

27-04-2015, 15:08

Description

Development (Fig. 22.1)

The pupil at birth has a small diameter, which is obviously associated with a weakened tone of sympathetic innervation. Premature babies with a gestational pattern of less than 32 weeks have incomplete pupil formation. Mydriasis is not a direct sign of damage to the central nervous system, sluggish pupil reactions are not a direct indication of a disorder of the afferent innervation.

Congenital and structural anomalies

• aniridia;
• microcoria (its congenital idiopathic form);
• polycoria and corectopia;
• coloboma;
• persistent pupillary membrane;
• congenital mydriasis and miosis;
• irregular pupil shape.

The study is carried out in a dimly lit room. A bright light beam is directed to each eye in turn. The child must look into the distance during the entire time of the study. First, for several seconds, the best (or healthy) eye is illuminated, and then the light beam is quickly transferred to worst eye. If the conductivity of the pupillomotor fibers in the second eye is worse, then both pupils will dilate, regardless of the presence of a light stimulus. Afferent pupillary reaction disorder is a sensitive test even in children, positive result in this study is not uncommon even with normal visual acuity and intact color vision especially in compression disorders.

Damage to the entire optic tract can be combined with a mild contralateral afferent pupillary reaction disorder, which is rarely detected in practice. Diseases of chiasma are not accompanied by a symptom of Marcus Hun.

Violations of the relationship between the reactions of the pupil to light and to the accommodative reflex
When the pupillary reaction is better expressed to the accommodation reflex than to light, we are talking about the violation of the relationship between these states. In order to make sure that this disorder is present, a bright light is needed. Apparently, the disorder occurs as a result of damage to the pupillomotor fibers in the spinal cord, in the area localized between their branching from the visual pathway, but before their connection with the fibers of the accommodative reflex in the nuclei of Edinger-Westphal (Edinger-Westphal).

Symptom Argyll Robertson (Argyll Robertson)
The pupil is small in diameter, irregular in shape, the accommodative reflex is more lively than the reaction of the pupil to light. Pupil dilation is slower than normal. Slit-lamp examination often reveals iris atrophy. Pathology is usually observed in adults with tertiary syphilis, but can occur in children and adolescents against the background of congenital syphilis. There are reports of the possibility of manifestation of Argyle-Robertson's pseudosymptom in patients with diabetes after reaching the age of 20. The pupil retains its normal diameter.

sylvian aqueduct syndrome
Compression of the dorsal part of the midbrain by a growing tumor (pinealoma, epindymoma, trilateral retinoblastoma, granuloma) can cause a violation of the relationship between the accommodation reflex and the pupil's reaction to light. In such cases, the pupil at rest has an enlarged diameter.

Associated symptoms include vertical gaze palsy, eyelid retraction, accommodation disorder, convergence-retraction nystagmus, and strabismus associated with convergence paralysis.

Segmental pupil reactions
In some circumstances, one of the segments of the iris sphincter begins to react more intensely than others. This phenomenon occurs when following states.

Adie's syndrome (tonic pupillary syndrome)
The syndrome sometimes manifests itself in children, but more often occurs at an older age, especially in young women. The disorder is usually unilateral, although sometimes bilateral pathology. On the affected eye acute process pupil has a slightly larger diameter than healthy eye, and expands more slowly in the dark.

Segmental pupillary sphincter palsy may be present with delayed and undulating pupillary response to light. It is combined with an accommodation disorder, more pronounced in the acute phase of the disease, but gradually, after 1-2 years, disappearing. With gynermetropic refraction, it is necessary to take into account the possibility of anisometropic amblyopia.

Other Symptoms Associated with Tonic Pupil Syndrome

• decreased sensitivity of the cornea in the affected eye;
• decreased reflexes of the limbs.

• orbital tumors;
• syphilis;
• diabetes;
• Guillain-Barre syndrome;
• Miller-Fischer syndrome (Miller-Fischer);
• paidisautonomy;
• hereditary sensory neuropathy:
• Charcot-Marie-Tooth disease (Charcot-Marie-Tooth);
• trileyoma poisoning;
• paraneoplastic disease with autonomic neuropathy and chronic recurrent polyneuropathy.

Episodic pupillary dysfunction ("bouncing" pupil)
There is an episodic mydriasis lasting from several minutes to several weeks and, as a rule, is accompanied by blurred vision and headaches.

There are reports of the possibility of changes in the shape of the pupil against the background of spasms of the iris dilator in young healthy people. The pupil can stretch for several minutes in one direction, taking on the shape of a tadpole. The disorder is due to a combination of reasons, which gives rise to the emergence of a category of patients with a "jumping" pupil.

Paradoxical pupil reaction
An unusual phenomenon in which the size of the pupil in the light is larger than in the dark. This condition was first described as pathognomonic of congenital stationary night blindness. Later, there were reports of the association of this disorder with the pathology of the cone apparatus of the retina, Leber's amaurosis, dominant optic nerve atrophy, and even with amblyopia. The presence of a paradoxical pupillary reaction in young children with nystagmus is an indication for the study of an electroretinogram.

Horner's syndrome
Horner's syndrome is a violation of the sympathetic innervation of the eyeball. The symptom complex of the syndrome includes: Miosis. The reaction of the pupil to light and the accommodative reflex were not changed. Pupil dilation in the dark is slow or absent.
Ptosis. Usually ptosis occurs upper eyelid 1-2 mm, accompanied by a rise of the lower eyelid by 1 mm. The narrowing of the palpebral fissure gives the impression of enophthalmos. Heterochromia.

In some cases congenital syndrome Horner found a lighter color of the iris on the affected side. However this symptom cannot be regarded as pathoggiomonic for congenital Horner's syndrome. Cases of heterochromia have also been described in patients with an acquired disorder (Fig. 22.5).

To confirm Horner's syndrome, pharmacological tests are performed using the following drugs:

1. Cocaine - in Horner's syndrome, unable to dilate the pupil.
2. Hydroxnamfetamine - with damage to neurons of the first and second order, it helps to dilate the pupil, but is ineffective in postganglionic disorder.
3. Adrenaline 0.1% - cannot fully dilate the pupil, but has an effect in postganglionic Horner's syndrome with deprivation hypersensitivity.

1. Birth trauma internal carotid artery and her sympathetic nerve plexus. The anamnesis, as a rule, contains the use of forceps in childbirth. These children have postganglionic Horner's syndrome.
2. Generic or surgical trauma preganglionic sympathetic pathway. This group includes patients with damage to the brachial plexus, known as Klamke's paresis.
3. Patients with manifestations of Horner's syndrome and the absence of birth injury history, but clinical symptoms damage to the area of ​​the peripheral and / or superior cervical ganglion. For these patients, ipsilateral absence of sweating is pathogiomonically.

Includes:

1. central damage. Occurs with trauma to the brain stem, tumors, malformations vascular system, heart attacks, hemorrhages, enringomegaly and in comatose patients.
2. Pregaglionic lesions. Observed with neck injuries, non-problastoma and other tumors of the neck.
3. Damage to the postganlion neuron of the superior cervical ganglion. Occur in the pathology of the cavernous sinus, neuroblastoma and trauma.

Pharmacological preparations

Pupil dilating drugs
Parasympatholytics
These drugs dilate the pupil and cause cycloplegia. Their use may be complicated by respiratory distress in children with congenital hypoventilation. central origin or seizures in brain disorders.

Most often used:

• atropine 0.5-1.0%;
• homatropin 2%;
• cyclopentolate 0.5-1%;
• tropicamide 1%;
• hyoscine 0.5%.

These drugs include:

• adrenaline 0.1-1.0%;
• phenylephrine 2.5-10%.

Anticholinesterase drugs
These drugs are used to treat glaucoma and accommodative strabismus.

These include:

• phospholine iodide (Ecothiopat) 0.03-0.125%;
• ezerin 0.5%;
• isofluoropath 0.025%.

• guanitidine (Ismelin) 5% - sometimes used to treat eyelid retraction in hyperthyroidism;
• thymoxamine 1%.

Some antihistamines and antidepressants cause mydriasis.

Heroin, morphine and other opiates, marijuana and some others psychotropic drugs cause bilateral pupillary constriction.

Pathology of the accommodation reflex

Acquired disorders
Syndrome Silyeeeea aqueduct (Parino)
Gross changes in accommodation in preterm infants are one of the symptoms of tumors that occur in the midbrain and are accompanied by such classic manifestations as convergence-retraction nystagmus, vertical gaze disorders, eyelid retraction, convergence disorders, pathological changes pupillary responses to light and accommodation.

Common diseases
Botulism, diphtheria, diabetes, head and neck trauma can cause accommodation disorders, either isolated or combined with disorders of eyeball movements and convergence. There are reports of accommodation disturbances in Wilson's disease.

Eye diseases
Accommodation defects are seen in children with severe iridocyclitis, lens dislocation, large colobomas, buphthalmos, high myopia, and eye trauma, including retinal detachment surgery.

Other neurological causes
Accommodation disturbances often accompany a tonic pupil in Adie's syndrome and paralysis of the third pair of cranial nerves.

Pharmacological preparations
See above.

Psychogenic factors
Adolescents may have difficulty reading without any organic causes. The correct approach to the child helps to achieve a normal accommodative response.

Accommodation in schoolchildren
Although in healthy children the area of ​​accommodation is not changed, in some cases a pathologically low amplitude may appear in schoolchildren. It is not known whether there is a statistical relationship between low accommodation amplitude and learning disability.

Spasm of accommodation
Spasm of accommodation consists in an episodic combination of accommodative pseudomyopia, weakening of convergence and constriction of the pupils. Patients present with asthenopic complaints, including blurred vision, double vision, and eye pain. The disorder can be caused by hypercorrection of myopic patients, but in most cases no organic pathology is detected. Apparently, the phenomenon has a psychogenic character.

However, in some cases, accommodation spasm accompanies such serious diseases as:

• neurosyphilis;
• myasthenia gravis;
• multiple sclerosis;
• encephalitis.

Anisocoria

Physiological anisocoria
Often seen in healthy people. The difference in pupil size at rest rarely exceeds 1 mm. The difference in size persists both in the light and in the dark. This symptom is important differential diagnosis with Horner's syndrome or parasympathetic disorder.

If the patient has Horner's syndrome, the difference in pupil size will be greatest in the dark. With a disorder of parasympathetic innervation, the difference in pupil size is most pronounced in bright light. And, finally, in physiological anisocoria, the difference between pupil diameters remains unchanged regardless of the intensity of illumination.

PUPILS, SHAPE CHANGES, VALUES, mobility. The state of the pupils and their reaction have diagnostic value both in ophthalmic and in some common diseases organism. Distinguish between pupillary constriction (miosis), pupillary dilation (mydriasis) and unequal value pupils (anisocoria). There are also violations of pupillary reactions. Bilateral constriction of the pupils is noted with irritation of the third pair of cranial nerves, which may be associated with a disease of the central nervous system. Unilateral damage to the sympathetic innervation sometimes gives a triad of symptoms: narrowing of the palpebral fissure, pupillary constriction, and small enophthalmos (Horner's syndrome).

In case of a disease of syphilitic origin (taxes of the spinal cord, progressive paralysis), Argyle Robertson's syndrome is often noted - bilateral miosis, anisocoria, irregular pupil shape, lack of reaction to light and preservation of the reaction to convergence and accommodation. This syndrome is observed not only in syphilitic lesion central nervous system, but also in other diseases (brain tumors, encephalitis, meningitis, traumatic brain injury).

Argyle Robertson Syndrome should be differentiated from the tonic reaction of the pupils to light (see Edie's syndrome), due to autonomic dysfunction. In Edie's syndrome, there is a unilateral pupil dilation and a sharp weakening of the pupil's reaction to light and convergence. In contrast to Argyle Robertson's syndrome, the pupils dilate well under the action of atropine. With a large pupil width, first of all, one should think about artificial mydriasis caused by ingestion of preparations containing belladonna. At the same time, there is a lack of reaction to light and a decrease in vision, especially at close range due to paresis of accommodation. A wide and fixed pupil is noted in blindness due to damage to the retina and optic nerve. The presence of a direct reaction to light does not exclude blindness due to the lesion. central department visual pathway above the level of the outer geniculate body. This happens after suffering basal meningitis, with uremia and other general intoxications.

Damage to the oculomotor nerve leads to pupil dilation with no direct reaction to light. If fibers leading to the ciliary muscle are simultaneously involved in the process, accommodation is paralyzed. In such cases, the diagnosis of internal ophthalmoplegia is made. It is observed in cerebral syphilis, meningitis, encephalitis, diphtheria, as well as in diseases of the orbit or in trauma with damage to the oculomotor nerve or ciliary node. Unilateral pupillary dilation occurs due to irritation of the cervical sympathetic nerve (increased lymph node on the neck, apical focus of the lung, chronic neuritis, etc.). Less commonly, unilateral pupillary dilation occurs with syringomyelia, poliomyelitis in meningitis, affecting the lower cervical and upper chest part spinal cord.

Clonic pupillary spasm (hippus)- a kind of pupillary reaction, when, regardless of the action of light, rhythmic contractions and expansions of the pupil occur. Occurs at multiple sclerosis, sometimes chorea and epilepsy.

Rarely, a paradoxical pupillary reaction is observed, in which the pupil dilates in the light, and constricts in the dark. It can be with syphilis of the central nervous system, tuberculous meningitis, multiple sclerosis, trauma of the skull, neuroses.

The shape, size and reaction of the pupils to external stimuli are of great diagnostic value. The main anomalies of the pupils are shown in the figures.

2. What is the normal pupil size?

It depends on age. The pupils are the widest in childhood (at 10 years old - 7 mm in diameter). With age, they gradually narrow (by the age of 50, their size decreases to 5 mm). This property of the pupils may be important for amateur astronomers and nocturnal bird watchers. In addition, it should be noted that because of this property of the pupils, the child's gaze seems to be more penetrating. Japanese cartoonists like to draw large eyes with huge pupils for their characters. The Italian ladies of the Renaissance knew about it important property pupils and used to dilate them with a preparation of a plant containing atropine. The plant received the Italian name belladonna, i.e. beautiful woman(in Russian - beauty). This method of attracting attention has long been the property of history, as it disrupted accommodation and caused other side effects.

3. How is the pupil examined?

The study is carried out in a dark room. The subject is asked to fix his gaze on some distant object and direct the beam of a flashlight into his eyes to make sure that the pupils are round and of the same diameter.

4. What should be paid attention to when examining the pupil?

On the shape, size and reaction to external stimuli - accommodation and reaction to light, direct and friendly. Under the direct reaction is meant the reaction of the pupil of the eye into which the light is directed, under friendly - the reaction of the pupil of the other eye.

5. What is the unique feature of the reaction of pupils to light?

The reflex arc of this reflex includes cross paths, so the sphincters of both pupils receive the same impulses from the midbrain.

6. What is anisocoria?

This is the asymmetry of the pupils (the term consists of three Greek roots: an - absence, iso - the same and core - the pupil). Anisocoria indicates a unilateral lesion of the iris or efferent innervation (oculomotor nerve or sympathetic nerve fibers). In the latter case, efferent impulses partially or completely do not reach the sphincter of the pupil from the affected side. With damage to the afferent innervation, anisocoria does not develop, since, due to the structural features of the afferent pathways in the central nervous system, afferent impulses from the retina of one eye reach the nuclei of both oculomotor nerves.

7. What is accommodation?

This is the ability of the eye to reflexively adapt to the distance to the object under consideration, which is provided by the interaction of three structures: the sphincter of the pupil (smooth muscle fibers of the iris narrowing it); medial rectus muscle, as a result of the contraction of which convergence occurs; ciliary body, with the contraction of the muscle fibers of which (the ciliary muscle) the curvature of the lens changes. In Argyll Robertson's syndrome, accommodation is usually preserved.

8. What are the most common pupil shape anomalies?

Probably the most common anomaly is an uneven pear-shaped pupil after intraocular surgical interventions such as removal of the lens for cataracts. In the initial stage of herniation of the hook of the brain, before the pupils become wide, perfectly round and cease to respond to light, they acquire an oval shape. The oval shape of the pupil is also observed in Adie's syndrome.
At blunt trauma eye, a rupture of the sphincter of the iris may occur, as a result of which the pupil enlarges and acquires uneven outlines.
With iritis (inflammation of the iris), its adhesions (synechia) are formed with the anterior wall of the lens capsule, due to which the pupil becomes uneven.
Iris coloboma is a malformation of the eye, a consequence of incomplete fusion of the embryonic fissure of the eye cup, in which the pupil has the shape of a keyhole, most often directed with a narrow part down and towards the nose.

9. What is hippus?

A synchronous fluctuation in pupil size that occurs spontaneously or in response to exposure to light directed directly into the eye. The term comes from the Greek word hippos (horse) and is a metaphor that likens the fluctuations in the diameter of the pupil to the rhythmic up and down movements of the legs of a galloping horse. Unlike the so-called pupil of Markus Hahn, hippus is not associated with a disorder of the afferent innervation.

Note: With hippus, the pupil first reacts to light by constriction, while with a defect in afferent innervation, it expands, which is easy to notice by quickly moving the beam of a flashlight back and forth in front of the eyes of the subject.

10. Name the mechanisms that regulate pupil size.

Two mechanisms: parasympathetic (via the oculomotor nerve) for the pupillary sphincter and sympathetic (via the cervical sympathetic nodes) for the dilator. Parasympathetic denervation leads to mydriasis (dilation of the pupil), sympathetic - to miosis (narrowing).

11. What are the main causes of anisocoria (incongruity of pupils).

Physiological (simple) anisocoria. Normally, the difference in the diameter of the pupils is at least 0.4 mm, which is due to the unequal tone of the sphincters of the pupils of the right and left eyes. Physiological anisocoria is the most common variant. It is observed in 3% of people constantly, and in 20% - from time to time. Unlike pathological, with physiological anisocoria, the difference in pupil diameter does not change depending on the illumination. In addition, physiological anisocoria is constant, rarely exceeding 1 mm, and is never accompanied by other symptoms (ptosis, diplopia, and light-near dissociation - see below). On the contrary, in their presence, anisocoria is an alarming symptom.

pupil dilation medicines - another frequently encountered benign variant, the result of intentional or accidental instillation of mydriatic in the eye (remember the Italian women of the Renaissance), or even careless use of an inhaler with some kind of anticholinergic agent. This makes it difficult to diagnose during intensive care patients with this or that level of oppression of consciousness. Temporary iatrogenic palsy is not relieved by instillation of cholinergic agents such as pilocarpine, which distinguishes it from mydriasis in Adie's syndrome or oculomotor nerve palsy temporarily relieved by instillation of cholinergic agents.

Paralysis of the oculomotor (III cranial) nerve, for example, due to parasympathetic denervation. It is characterized by: pupil dilation; ptosis (paralysis of the muscle that lifts the eyelid); paresis of all oculomotor muscles, except for the lateral straight line and the upper oblique from the side of the lesion - the only ones of the ophthalmic that are not innervated by this nerve; diplopia due to abduction of the eye outward and downward. When instilled with cholinergics, the dilated pupil narrows. Due to the weakening of the sphincter of the pupil, anisocoria becomes more noticeable in bright light.

Horner's syndrome first described by the Swiss ophthalmologist Johann Friedrich Horner (Horner) in 1860. It is characterized by pupillary constriction due to dilator paralysis and ptosis due to paralysis of the levator eyelid muscle on the affected side, as well as anhidrosis of the face on the same side due to sympathetic denervation. Unlike physiological anisocoria, the difference in the diameter of the pupils in Horner's syndrome depends on the illumination - it becomes more noticeable in the dark due to insufficient expansion and less noticeable in bright light, since the function of the sphincter is preserved.

For differentiation, instillation of cocaine into the eyes is also used - physiological anisocoria after it decreases, caused by Horner's syndrome - increases. The cocaine test is very informative: its sensitivity and specificity reach 95%, positive odds ratio - 96.8, negative - 0.1. Most common cause Horner's syndrome in patients admitted to neurological departments - damage to the upper motor neurons, such as a stem stroke. In such cases, a thorough neurological examination is necessary with special attention to manifestations lateral syndrome midbrain.

Damage to the corresponding second-order motor neurons is most often associated with lung tumor or , which is of particular importance in the practice of departments of internal diseases and requires a thorough examination of the organs of the neck and chest. Finally, lesions at the level of the lower motor neuron may be the cause of Horner's syndrome. With them, anhidrosis of the face does not develop. Less common causes of this syndrome are migraine, trauma or inflammation in the orbit, cavernous sinus syndrome.

Other reasons: inflammatory processes (iritis of one eye); effects trauma; acute angle-closure glaucoma, various neurological diseases; transferred ophthalmosurgical interventions (for example, extraction of the lens for cataracts). Anisocoria in combination with conjunctival hyperemia requires the exclusion of severe eye diseases.

12. What are the most common causes of oculomotor (III cranial) nerve palsy?

Pressing the nerve to the free edge of the cerebellar tenon due to the rapid expansion of the aneurysm of the posterior communicating artery or wedging of the hook of the brain from the side of paralysis. It is accompanied by a sharp mydriasis with the absence of direct and friendly reactions of the pupils to light (the pupil of Hutchinson), depression of consciousness, ptosis and ophthalmoplegia. It should be noted that the increasing mass formation is usually localized on the same side as mydriasis, ptosis and ophthalmoplegia, since all these symptoms are due to paralysis of the oculomotor nerve. On the same side, hemiplegia is localized, since it is caused by damage to the brain stem on the opposite side.

13. What is an aneurysm of the posterior communicating artery?

This is the most common aneurysm cerebral vessel. In 96% of cases, it is accompanied by partial or complete paralysis of the oculomotor nerve with such manifestations as mydriasis, ptosis and ophthalmoplegia. Mydriasis from the aneurysm is observed in 20-60% of cases. This facilitates topical diagnosis, which is very important, since surgery is necessary to prevent aneurysm rupture.

14. Who is Hutchinson?

Sir Jonathan Hutchinson, an English surgeon and pathologist (1828-1913), described the pupil picture named after him in 1865. A devout Quaker, Hutchinson went on many charitable missions and intended to remain a missionary doctor, but instead became one of the most versatile clinicians of the 19th century. century, highly valued by another eminent English doctor Sir James Paget.