Determination of visual acuity: rules, methods, tables

When checking vision in children and adults, ophthalmologists use various techniques to accurately determine the diagnosis. Using an ophthalmoscope, the doctor can evaluate the condition of the lens, vitreous body and retina of the eye. This device makes it possible to look inside the pupil and identify incipient unwanted changes. But an ophthalmoscope does not always allow you to examine the structure of the eye. When a light beam is directed at the pupil, which must be used for a detailed examination of the organ, the eye reflexively narrows and the doctor is unable to establish an accurate diagnosis. In this case, special drops that dilate the pupils come to the rescue.

Indications

Substances for the expansion of the pupils are also prescribed by ophthalmologists to eliminate spasms of accommodation. This pathology occurs during long-term intensive work (for example, with a PC or while reading), which leads to increased negative effects on vision. Consulting with a specialist will help you avoid getting confused about the types of medications.

There are two types of such medications:

straight – promote muscle contraction;
indirect – impact on the orbicularis muscle, reducing the intensity of contractions.

They are widely used for inflammatory diseases of the iris and ciliary body, which helps bring it to a state of calm and reduce the number of complications.

List of drops for dilating pupils

Here is a list of the most popular and effective eye drops for dilating pupils.

Atropine

Atropine 1% is the oldest drug from the mydriatic group. It began to be used about two hundred years ago, by dropping the juice of henbane, belladonna or dope into the eyes (or ingesting it internally). According to historical data, Helmholtz in the mid-19th century used substances containing atropine during eye examinations.

The mechanism of action of atropine is to block m-cholinergic receptors located in the smooth muscles of the iris, thereby relaxing it. This leads to dilation of the pupil and paresis of accommodation (it is impossible to properly examine objects either near or in the distance). Maximum mydriasis occurs after 30-40 minutes, and paralysis of accommodation occurs after 1 hour. This effect lasts for 7-10 days after a single instillation. Due to such a long-term persistence of mydriasis, atropine is currently used mainly in a 24-hour ophthalmology hospital in the treatment of children with visual impairment, or after eye injuries to prevent pupillary fusion.

Atropine 1% eye drops are sold only by prescription as they are a potent drug. Its price in pharmacies does not exceed 50 rubles.

Phenylephrine

A more modern substance for creating artificial mydriasis. Phenylephrine causes mydriasis due to its effect on alpha-adrenergic receptors (it is an analogue of adrenaline), while it does not affect the ciliary muscle. This means that cycloplegia does not occur, causing pupil dilation to persist for 4-6 hours without much visual impairment. This time is always enough to conduct an examination, perform an operation, and prevent the development of adhesions in the treatment of iridocyclitis.

Phenylephrine is sold in pharmacies under various trade names:

Irifrin 2.5% and 10% (Sentisse, India). A 2.5% solution is prescribed primarily for the treatment of children with accommodation disorders, as well as for short-term pupil dilation for diagnosing the posterior segment of the eye. 10% Irifrin is intended for the treatment of uveitis (breaks the adhesions between the iris and the anterior capsule of the lens). Despite the high price (600-700 rubles) it is the most prescribed mydriatic drug in Russia.
Irifrin BC 2.5% differs from the usual Irifrin only in that it does not contain the preservative benzalkonium chloride, which when instilled drops often causes discomfort and pain in the eyes, which children especially complain about. Accordingly, Irifrin BC is easier to tolerate. The price of Irifrin BC is the highest among all mydriatics: on average 650-700 rubles for 15 small dropper bottles.
Neosinephrine-POS 5% and 10% (Ursafarm, Germany) is an inexpensive (about 290 rubles), but unpopular analogue of Irifrin produced in Germany. Available in most pharmacy chains.
Phenylephrine-optic 2.5% (LEKKO, Russia) is the cheapest drug based on phenylephrine (220 rubles), but for unknown reasons, it is unpopular in Russia.

Cyclomed

Cyclopentolate belongs to the group of m-anticholinergic blockers, and acts on the iris and ciliary muscle in the same way as atropine, but more “gently”. After a single instillation of Cyclomed, pupil dilation occurs (due to relaxation of the circular muscle of the iris) and accommodation paresis (cycloplegia) occurs within 25-40 minutes, which usually persists for 8-12 hours.

The drug is used primarily for diagnostic purposes in clinics and or ophthalmological hospitals, as well as before surgical treatment of cataracts and vitrectomy.

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Tropicamide

Tropicamide eye drops also belong to the group of m-anticholinergics, like atropine and cyclomed, but have two advantages over them:

Pupil dilation and paralysis of accommodation occur within 10-15 minutes (for brown-eyed people after 20-25 minutes), which speeds up diagnostics in clinics;
The wide pupil remains for 30-40 minutes - this allows you to get behind the wheel and engage in daily activities almost immediately after examination by a doctor.

Tropicamide is sold in pharmacy chains by prescription under the following trade names:

Tropicamide 0.5% (Rompharm, Romania) is the leader in government procurement in the mydriatic category, as its price is only 48 rubles.
Midriacil (Alkon, Belgium) is a very popular drug that is often prescribed by ophthalmologists for treatment, and is also used in daily work to dilate the pupil.
Tropicam (Scan Biotech, India).

All of the drugs listed are prescription drugs, and it is impossible to buy them in pharmacy chains without a special doctor’s prescription (Form 148). This is due to the fact that drug addicts began to add it to intravenous drugs to enhance the narcotic effect and reduce the dose taken (mainly heroin) by almost 2 times. This has significantly complicated the treatment of patients with iridocyclitis, uveitis, and other inflammatory diseases of the anterior segment of the eye. In this regard, the drug Midrimax was developed.

Midrimax

About a year ago, the company Sentiss (India) released the drug Midrimax, which contains tropicamide and phenylephrine. This combination of substances turned out to be very successful:

Pupil dilation occurs within 10-15 minutes and lasts for an average of 4 hours, which allows the drug to be used not only for diagnosis, but also for the successful treatment of iridocyclitis;
Midrimax is approved for free sale in pharmacies. Since it contains phenylephrine, drug addicts, when administered intravenously with such a solution, experience all its “side effects”: increased blood pressure, difficulty breathing, headaches, difficulty urinating, etc. The only drawback of Midrimax is its rather high price - about 500 rubles. Only Irifrin and Irifrin BC are more expensive.

Features of the procedure

The medicine is administered with a pipette dispenser for therapeutic and prophylactic purposes. Subsequently, the drug enters, which acts on the muscles that control the pupil, its expansion occurs due to the interaction of receptors.

The receptors lose their ability to control the visual system for some time and relax. The validity period depends on what components are included in the composition. On average, the effect on receptors lasts from 2 hours to 2 days. For people with light eyes, this lasts longer than for people with brown eyes.

What is mydriasis?

Permanent or temporary dilation of the pupils is often observed when taking alcohol, drugs or psychotropic drugs. This effect can persist for a long time even after a person has stopped using these substances. This condition is called mydriasis; it does not go away even in bright light. Mydriasis sometimes results from certain diseases, in particular:

glaucoma;
traumatic brain injury or intracranial bleeding;
epilepsy;
botulism;
some infectious diseases, in particular encephalitis or meningitis;
prolonged migraines;
tumor processes in the brain;
eye injuries.

If you suspect at least one of the listed diseases and dilated pupils are unnatural for you, you should urgently consult a doctor.

When is it prescribed?

They are prescribed to the patient at night, which, in fact, helps to reduce blurred vision and failure to focus, which can lead to difficulties in everyday life (study, work, driving).

This technique is used to diagnose the fundus. An expanded pupil gives the physician a chance to examine the fundus of the eye more carefully and promptly see the development of the disease (detachments, degenerative changes, various injuries). If the patient suffers from false myopia, the drops can be used for both research and therapeutic purposes. They also remove muscle tension that appears if a person performs work for a long time that is associated with eye strain. This medicine is widely used for inflammatory processes in the iris and ciliary body (iritis, iridocyclitis).

Doctors recommend using it in the following cases:

When examining the lens;
When measuring refraction;
During retinal surgery;
In the treatment of diseases;
For prevention.

In conclusion

A thorough eye examination requires special attention. If it is necessary to accurately diagnose the condition of the eye system, doctors must instill special drops into the eyes. Modern drugs do not cause side effects and do not affect the visual perception of the surrounding world. This is a high-quality way to quickly identify the cause of any ophthalmological disease. Answering the question: why do doctors put drops into the eyes during an examination, now every patient knows that this is a necessary procedure to diagnose the condition of the pupil.

Side effects

Using drops, most patients complain of a slight burning sensation in the eyes, but do not be afraid of this, this effect is considered normal. But there are also a number of side effects, which include: failure of accommodation, a feeling of double vision, intraocular pressure, fear of light rays, photophobia, redness of the eyelid area, conjunctiva, hypersensitivity, dryness, increased body temperature, problems with urination, irritability, pain, turbidity , anxiety. If such problems arise, you should immediately seek help from a specialist. Independent prescription and use of pharmaceuticals is unacceptable; consultation with an ophthalmologist is necessary. Before the appointment, the doctor will determine the degree of intraocular pressure and find the medicine the patient needs.

Varieties

“Atropine” is a potent product, contains a number of contraindications, has a significant duration of action, and should not be used without its intended purpose.
"Mydriacyl" - starts working in thirty minutes and lasts no more than 3 hours.
"Irifrin" is a therapeutic and prophylactic agent. Not approved for use in children under 12 years of age, elderly people suffering from heart and vascular diseases.
"Cyclomed" - has a long-lasting effect.
“Mezaton” is best used according to prescription.

Table for determining visual acuity

For normal visual acuity (1.0 or “one”), the distinguished elements must have an angular size of 1', while the entire optotype has an angular size of 5' - this international agreement on the size of parts formed the basis for the creation of optotypes.

The method of testing vision according to the Golovin-Sivtsev table, placed in a Roth apparatus, is the most common in Russian clinics (in commercial ophthalmological centers they often use sign projectors from foreign manufacturers with a different set of signs).

Is it possible to dilate pupils at home?

To achieve this result, you can try the following exercises:

Close your eyes and imagine that you are in a dark room or space. Studies have shown that the pupils become larger than usual for a while, which relaxes the muscles.
Look at an object that is at a distance from you and focus your gaze on it.
Being in a bright room, turn your gaze to the dark part of it.
Thoughts about what makes adrenaline increase also give such results.

Why are the pupils constantly dilated?

If the pupils are constantly enlarged, this may be a sign of damage to the optic nerve. In this case, the person reacts extremely painfully to bright light and sees quite poorly in the dark. These symptoms are more common in adults than in children. It is recommended to begin treatment in a timely manner, and for persons driving a car, if possible, refrain from traveling in the dark.

Mydriasis does not require separate treatment: it goes away as soon as doctors eliminate the problem that caused it. In some cases, nootropic and neurotrophic drugs are prescribed to improve brain nutrition and blood supply to the eyes. If damage to the optic nerves is suspected, ophthalmologists determine its nature and prescribe appropriate treatment, therapeutic or surgical (depending on the general picture of the disease).

MagazinLinz.ru team