Vision 1.0. What does it mean?

After checking the vision in the ophthalmological room, the doctor always tells us his acuity. Normal 100% vision is usually referred to as 1.0 or "one".This value is usually determined using special tables with symbols (optotypes).When determining visual acuity, it is important to consider refraction. Therefore, it is impossible to carry out an objective check of vision at home using different tables on the Internet.

In this article, we will tell you how to check your eyesight in your ophthalmologist's office using a table of letters, what parameters the specialist should take into account, and what deviations can be diagnosed in the diagnosis of visual acuity.

Check of vision at the ophthalmologist

The most common way to check the eyes of an ophthalmologist is to use tables. There are several types of diagnostic tables:

1. Sivtsev's table.It is the most famous and widespread. The table consists of twelve lines containing the letters of the Russian alphabet. The higher the line, the larger the letter, and vice versa. At the left edge of the table, the letter "D" indicates the distance at which the patient with normal vision should determine all optotypes. On the right edge is the letter "V", which indicates visual acuity at a distance of five meters. Vision 1.0 - this is when a person sees the tenth line at a distance of five meters.
2. The Snellen table.Based on this table, the Sivtsev table was created. The Snellen table is used in countries where they speak English. It consists of eleven lines. In the top line there is only one large letter, then the letters decrease in size. Visual acuity is determined at a distance of six meters.
3. Orlova's Table.This table is used to test the eyes of children, so the letters here are replaced with pictures. The lower the line, the smaller the picture size. Visual acuity is defined similarly, as with the help of Sivtsev's table. Normally, children should see the tenth line well at a distance of five meters.
4. Table Golovin.The table consists of rings that are the same in size but have tears in different parts (right, left, top, bottom). Visual acuity is determined at a distance of five meters. Normally, a person should see two remote points with a minute angular resolution.

An ophthalmologist must check his vision according to certain rules, otherwise the result will be unreliable. This can affect the effectiveness of further treatment.

Between the chair where the patient sits, and the table should be a distance of exactly five meters. And at the eye level there should be the tenth line.

It is necessary that the table has a uniform illumination of seven hundred lux. It must be in front of the window.

Vision on each eye is determined separately. In this case, one eye should be covered with an opaque spatula, but not squeezed. The eye should also not be screwed up.

At full definition of visual acuity, one error is allowed when reading optotypes of three to six lines.In determining the optotypes of the seventh line and thereafter, two errors are allowed.A person should see the symbol in two or three seconds.

Visual acuity

Visual acuity is the ability of the eyes to see two luminous dots separately from each other under the smallest angle of view.The normal viewing angle should be one minute.

The definition of visual acuity is called visometry, more details can be found here.

Golovin's Table

Definition of visual acuity

The definition of visual acuity is necessary to assess how patient can distinguish details.Therefore, the severity is determined both at a close distance, and on a remote one.

To test vision in the distance, a person needs to determine the optotypes presented on the table (the kinds of tables were considered earlier) or projected onto the screen.The patient should read the letters to which the ophthalmologist will tell him, or identify the symbols, pictures.

For those who wear glasses or contact lenses, eyesight is checked with corrective lenses.

All about color contact lenses read in this article.

To check the vision near, a person should read the text, in which the letters have different sizes.

According to the results of the check, it can be found out that the vision is not a unit.The further task of the ophthalmologist is to conduct a refraction study in order to establish the cause of the decrease in visual acuity.

Refractive vision

Refractive vision refers to the process of refraction of light rays in the optical system of the eye.Curvature of the lens and cornea, as well as the distance between them determine the refractive power of light.

Types of refraction:

• EmmetropiaNormal refraction.
• Myopia- people do not see well in the distance.
• Hyperopia- a person sees badly near.

With normal refraction, the rays of light intersect in the focus of the retina, so a person can see all objects at any distance.To get a clear image of an object located close, the eyes strengthen their refractive power, thereby increasing the accommodation.With farsightedness, the eyes have a weak refractive power.The rays of light intersect behind the retina. Therefore, the eyes are forced to increase the force of refraction, even when a person looks into the distance.

And with myopia, the eyes have a great refractive power, because the light rays converge before the retina.

The higher the degree of myopia or hyperopia, the worse the quality of vision.

Both these pathologies have three degrees:

1. Weak degree - no more than three diopters.
2. The average degree is from four to six diopters.
3. High degree - more than six diopters.

Determination of refraction

To determine the refraction use a special unit of measurement - diopter. This unit is needed to denote the strength of refraction.The procedure for determining refraction is called refractometry.

How to choose the correct glasses for your eyes see here.

Laboratory Refractometer

Refraction is determined using optical glasses or a special refractometer.

Refraction can be different for both eyes. It happens that one eye is nearsighted, and the other is far-sighted. This is called anisometropia.

One of the methods for determining refraction is retinoscopy.This method consists in observing the movement of the shadow in the pupil lumen. For this, the patient and ophthalmologist go to a darkened room, where the doctor shines in the patient's pupil with a syaskop and watches the shadow.Its direction of movement depends on refraction.Retinoscopy is necessary to determine refraction in children.

The measurement process for retinoscopy

In order to automatically determine refraction, an ophthalmologist can use such devices as an autorefractometer or aberrometer.The first device allows you to assess the focus of the rays relative to the retina, to identify the direction and magnitude of astigmatism.And the second device makes it possible to determine the imperfections of the eyes.

Deviations

Myopia

Myopia or myopia is a disease in which a person does not see well in the distance. In this case, the image is not focused on the retina, but in front of it.Vision becomes so fuzzy due to the fact that the optical system ceases to correspond to the length of the eye.

When myopia the eyeball increases.

Myopia is congenital and acquired.Sometimes it can progress.Therefore, the goal of vision correction with myopia is the weakening of the refractive power of the eyes, so that the image is focused on the retina.

Symptoms of myopia:

• Long-range vision deteriorates;
• The contours of objects become indistinct;
• Objects can merge with each other, double, distort;
• Near vision is preserved.

There is such a thing as false myopia.In this case, because of the overstrain of the lens muscle, there is a spasm of accommodation. False myopia is treated with medications and special exercises for the eyes.

How to treat a spasm of accommodation will tell this article.

Myopia is very dangerous in that it can lead to dystrophy and detachment of the retina.

Hypermetropia

Hypermetropia or hyperopia is a disease in which a person does not see well near. The image of the subject is focused behind the retina.Hypermetropia develops because of a short eyeball or because of a weak refractive power.

With age, there is an even more significant impairment of vision, since the eyes lose their accommodative capacity - the lens becomes less elastic, its muscles become weaker.

Symptoms of hypermetropia:

• Vision becomes clouded;
• Fast fatigue of the eyes, there is a feeling of discomfort;
• Disruption of accommodation and binocular vision;
• Vision is reduced functionally (amblyopia);
• There may be strabismus.

Hyperopia is simple, pathological and functional.Simple or physiological hypermetropia is observed when the eye is shorter than necessary for the focus of light rays on the retina.Pathological hypermetropia develops with various pathologies of the eyes, traumas. A functional farsightedness is observed in case of accommodation paralysis.

Astigmatism

Astigmatism is a violation of refraction, which can often be combined with myopia (myopic astigmatism) and with hypermetropia (hypermetropic astigmatism).

With this pathology, the sphericity of the cornea and the lens is disrupted. Therefore, in different meridians the optical force is different, and part of the image can focus on the retina, and the other part - behind it or before it.

Astigmatism is corneal and lens-like. By its nature, it is divided into:

• Congenital.It occurs in childhood and does not affect visual acuity, but only if it does not exceed half the diopter. If the astigmatism is more than one diopter, the vision is significantly reduced, and treatment is required (correction with glasses or lenses).
• Acquired. It occurs as a result of the appearance of scars on the cornea. Scars can result from injuries, surgeries, injuries.

Astigmatism can contribute to the development of strabismus and rapid deterioration of vision.

Video

Treatment of lachrymation in the elderly: what are the specifics and preparations.

Treatment of conjunctivitis with drops: http://eyesdocs.ru/zabolevaniya/konyunktivit/kakie-kapli-pomogut-vylechit.html

Symptoms and treatment for uveitis are discussed in this article.

conclusions

The vision test is just a necessary procedure. Without it, sometimes it's just impossible to notice any slight deterioration. Therefore, in order to avoid the appearance of such deviations as myopia, hypermetropia and astigmatism, and to preserve the unit, one should visit the office of an ophthalmologist at least once a year and follow its advice and recommendations.