Myos: a variant of the norm or a pathological process?

The constricted state of the pupil does not always refer to pathological phenomena. It occurs against the background of physiological causes in people of any age with fatigue or during sleep. But this condition, which has received the name "miosis" in medicine, can sometimes be a symptom of a pathological process occurring in the body.What diseases cause a narrowing of the pupil. Read more about this.

Definition of a symptom

Miosis is a medical term that characterizes a condition in which the pupil is narrowed to a considerable extent.A similar condition may be a variant of the norm (observed in certain situations) or signaling about any pathology.

Why does the size of the pupil change?The fact is that the size of the pupil varies constantly depending on many factors. This process is regulated by the tone of the internal muscles of the eye. The sphincter innervated by parasympathetic fibers provides pupil contraction (miosis), while the dilator, innervated by the fibers, is responsible for the increase (mydriasis).

The sphincter located in the iris, is not controlled by the human consciousness and is compressed reflexively at:

• The accommodation of the eye;
• Sudden increase in light intensity.

Miosis, as a physiological norm, is peculiar:

• For people of advanced age(over time, the accommodation of the eye changes, since the lens loses its elasticity);
• For newborn children;
• For persons suffering from hypermetropia;
• For all people in a state of sleep;
• When overexertion (physical and mental);
• As a reflex response to bright lighting;

Types and forms

Depending on the cause of the occurrence, there are several types and forms of miosis.Let us consider them in more detail.

Medicated myosis

It was provoked, as a rule, by taking a number of medicines, namely:

• Medications-adrenoblokatorov, reducing the activity of the adrenergic system;
• Drugs-holinostimulatorov;
• M-cholinomimetics(Muscarin, Pilocarpine);
• Preparations having M-cholin-potentiating effect (for example, Aminostigmin, organophosphorus compounds, etc.);
• Reserpine, barbiturates, opiates, cardiac glycosides, and others.

In addition, drug-induced narrowing of the pupil can occur in response to poisoning with such drugs and substances as:

• Morphine;
• Alcohol;
• Nicotine;
• Muscarin;
• Chloral hydrate;
• Bromine;
• Aniline dyes;
• Organophosphorus compounds;
• Caffeine;
• Mushrooms;
• Combat joints of the nerve-paralytic action (Zaman, Zarin).

Paralytic miosis

This type of miosis develops because of the paralysis of the dilator pupila, caused by a bilateral pathological process in the cervical section of the sympathetic trunk, the ciliospinal center, the intertwining of the carotid artery.

Spastic miosis

It can occur with spasm of the pupillary sphincter, as well as due to damage to the nervous system in diseases such as:

• Encephalitis;
• Meningitis;
• Syringomyelia;
• Tumors of the brain;
• Uremia;
• Multiple sclerosis in the phase of an attack.

Syphilitic miosis

It is one of the symptoms of a tertiary form of syphilis. In addition, syphilitic miosis can occur when:

• Foreign body in the cornea;
• Cornea ulcer;
• Sharp irrigation;
• Anterior and posterior uveitis;
• Horner's Syndrome;
• Traumatic hyphema.

  Scheme of uveitis

Forms

Physicians distinguish between two forms of miosis: two-sided and one-sided.

A bilateral miosis may be:

• Benign feature(with farsightedness or in old age);
• Normal response in bright conditions;
• Symptom of brain damage in the cerebellum or bridge(in this case the pupils become very small, which is called the "pinpoint");
• Symptom of some diseases (syphilis, diabetes).

  Manifestation of bilateral miosis

Bilateral miosis occurs during sleep, with increased intracranial pressure, in a deep coma.

One-sided miosis (anisocoria) is always a symptom of one of the following pathological processes:

• Horner's syndrome;
• Unilateral topical application of myotic preparations;
• One-sided local lesion in the anterior chamber of the eye;
• Irritation (irritation) of the third pair of cranial nerves;
• Syphilis(in rare cases).

  Manifestation of unilateral miosis

Causes

The causes of pathological narrowing of the pupils can be:

• Organic damage to the bridge in the brain;
• Vasoconstrictive action of pilocarpine;
• Action of morphine derivatives;
• Diabetes;
• Foreign body, caught in the cornea or her injury;
• Defeat of the fibers of the nervous system;
• Horner's syndrome, in which not only the pupil but also the eye gap narrows.

Two-sided narrowing of the pupils causes various neurological pathologies, most often tumors and hemorrhages. In this case, miosis is a neurological symptom and develops against a background of impaired consciousness. With neurological pathology, the pupils become very small, like the "pinpoint".

In addition, bilateral narrowing causes:

• ATInflammatory diseases of the brain(encephalitis, meningitis);
• Diabetes;
• Parkinson's disease;
• Epilepsy;
• Coma;
• Increased intracranial pressure;
• Atherosclerosis of carotid arteries.

  Increased intracranial pressure

A one-sided narrowed pupil is characteristic of Horner's syndrome. In this miosis is combined with the lowering of the upper eyelid and with a visible decrease in the size of the eyeball. Horner's syndrome is caused by a lesion that expands the pupil of the muscle, so it is more pronounced in the dark.

Among the causes of the Horner syndrome should be:

• Congenital anomalies of muscles and nervous system;
• Multiple sclerosis;
• Stroke;
• Brain tumors;
• Cervical osteochondrosis.
• Aneurysm of the aorta;

Diagnostic Methods

At first the doctor necessarily considers a variant of a miosis with a physiological deviation.Next, a diagnostic search is performed, which allows to identify the causes of pupillary narrowing and the relationship of this manifestation with the intake of medications.

Diagnosis of pupil narrowing by visual inspection using a slit lamp.Thus the ophthalmologist will necessarily check up reaction of a pupil on light, will examine an eyeground, will appoint perimetry, US, MRT eyes. If the reaction to light remains unchanged, then we are talking about a pathological violation, the cause of which should also be quickly established, as well as the diagnosis. Small pupils are formed during neurologic, vascular, ocular pathology, so the patient needs to undergo examination from a number of narrow specialists.

Slit Lamp

Treatment

Physiological myosis, which is more common than pathological, does not need treatment.If the pupils narrowed after taking medication, they will assume a normal state as soon as the drug that caused this symptom is removed from the body.

All other forms and types of miosis are eliminated immediately after the underlying disease that caused the narrowing of the pupils has been cured.

Usually enough:

• Get rid of the foreign body that got into the eyeball;
• Correct the carbohydrate and metabolic processes in the body.

  Foreign body in the eye

In more advanced cases, a tactic of treatment aimed at eliminating pathologies is being developed,due to which the pupils narrowed.

Paralytic, syphilitic and spastic miosis requires etiotropic therapy, with the help of which the underlying disease and its consequences will be eliminated.

Prevention

To avoid narrowing of pupils, it is necessary to remember that:

• Drugs are drunk strictly according to the doctors' prescription.
• Neurological disorders can not be triggered. This is one of the most insidious pathologies, the consequences of which negatively affect the patient's body. Periodic visits to the neurologist's office will avoid complications.
• With age, you need to more often examine the blood for glucose.
• Eyes - this is the body that needs protection, so use different protective devices in the conditions of long work at the computer, in production, as well as in the sun.

Video

conclusions

So,miosis is the narrowing of the pupil. This phenomenon in some cases is the norm, and in others - a symptom of dangerous diseases requiring immediate treatment. The information presented above in the article will help to understand why the pupils are narrowed. However, going to the doctor is a prerequisite for successful recovery from a possible pathology.