home All hormones Spectacle vision correction. Progressive spectacle lenses: selection method How to wear such glasses correctly

Spectacle vision correction. Progressive spectacle lenses: selection method How to wear such glasses correctly

23-10-2011, 06:58

Description

Spectacle correction is one of the types of ametropia correction.

A lens is an optical transparent body bounded by refractive surfaces, at least one of which is a surface of rotation. According to the shape of the refractive surfaces of the lens, they can be:

spherical(both surfaces are spherical or one of them is flat);

cylindrical(both surfaces are cylindrical or one of them is flat),

prismatic.

Convex lenses (convex or positive) have the property of collecting rays falling on them, which is used in the correction of hypermetropia. Concave (dispersive or negative) Lenses scatter light rays, which is why they are used to correct myopia. Cylindrical lenses used to correct astigmatism. Prismatic lenses find their use for the correction of heterophoria.

All materials used for the production of spectacle lenses are divided into two classes: mineral glass (inorganic materials) and plastics (organic materials). Regardless of its nature, the material must be transparent to the visible range of light rays, homogeneous and not have high dispersion for white light, i.e. do not cause chromatic aberrations.

Based on light transmission, lenses can be distinguished: colorless, colored (sun-protective), photochromic.

Lenses are divided into groups depending on the refractive index:

With a standard refractive index (1.54, for organic materials - 1.5);

Average index (1.64 and 1.56, respectively);

High index (1.74 and 1.6, respectively);

Ultra-high index (more than 1.74 and 1.7 and above).

The use of spectacle lenses with a higher refractive index makes it possible to reduce the thickness and improve their design, reducing the prismatic effect of the peripheral part of the spectacle glass.

Based on the number of optical zones, spectacle lenses are divided into:

Single vision;

Bi- and trifocal;

Progressive.

According to the design of the lens surface, there are spherical and aspherical.

primary goal any optical correction of refractive error - moving the focal point of the optical system of the eyeball to the retina.

Indications:

Hypermetropia;

All types of complex and mixed astigmatism;

Presbyopia;

Heterophoria;

Aniseikonia.

Contraindications are relative. These include the infancy of patients, some mental illnesses, and individual intolerance to eyeglass frames.

Astigmatism. Various types of astigmatism, accompanied by a decrease in visual acuity, are considered an indication for prescription of spectacle correction.

In this case, it is necessary to determine the spherical and cylindrical components of the correction and the cylinder axis. The size of the spherical component is determined according to the general rules for prescribing glasses for myopia and hypermetropia. The astigmatic correction component is prescribed according to subjective tolerability with a tendency to maximum values.

If, during an additional study of refraction under conditions of cycloplegia, other values of the size and position of the cylinder axis are determined, a cylindrical component of lower optical power should be prescribed. The position of the cylinder axis, determined under conditions of cycloplegia, is considered optimal.

It should be noted that early and timely prescription of optimal spectacle correction for various types of astigmatism makes it possible to achieve good tolerability of astigmatic glasses and their high efficiency.

Presbyopia. With presbyopia, visual performance at close range is reduced, and asthenopic complaints occur.

For optical correction, positive spectacle lenses are used, taking into account preliminary spectacle correction for distance.

In this case, they are guided by age norms. The first glasses with a positive component of +1.0 D are prescribed at the age of 40-43 years, then the strength of the positive glass is increased by 0.5-0.75 D every 5-6 years. At 60 years of age, the positive correction component is +3.0 D.

The cylindrical component of the correction, as a rule, remains unchanged.

When prescribing glasses for the correction of presbyopia, their individual tolerance and visual comfort when working at close range are taken into account.

To correct presbyopia, there are bifocal glasses with a distance zone and a near zone, which allows them to be used constantly.

Currently, progressive spectacle lenses with variable optical power are becoming increasingly common for the correction of presbyopia.

A progressive lens is a lens with a gradual change in the curvature of its surface from top (distance zone) to bottom (near zone). The optical power of such a lens also changes continuously.

A progressive lens has three optical zones:

Distance zone:

The near vision zone has additional optical power (the so-called addition), which provides the necessary correction for comfortable near vision;

Intermediate zone or “corridor of progression”.

These three zones blend smoothly into one another and provide clear vision at various distances. However, the presence of zones of different optical powers leads to distortions at the periphery of the lens, which limits the field of clear vision.

The designs of modern progressive lenses take into account the solution of certain problems. For example, lenses with a special design have been created for office work, providing comfortable vision at the distances required for office space. Progressive lenses have been created that are optimized for working on a computer or specifically for reading texts, for playing sports.

In general, progressive lenses do not provide high quality vision at all distances. Specialized lenses provide visual comfort over a limited range of distances.

Heterophoria(imbalance of the extraocular muscles). Correction of heterophoria with prismatic optical elements is carried out in the event of asthenopic complaints, i.e. phenomena of decompensation.

Prismatic correction is also advisable for paresis of the eye muscles and diplopia.

Prismatic lenses have the property of deflecting light rays towards the base of the prism. Correction of heterophoria is carried out using prisms, the base of which is located in the side opposite to the deviation of the eye. With exophoria, the base is turned inward, with esophoria, outward, etc.

Before prescribing prismatic elements, ametropia is corrected according to general rules. The total force of the prismatic component is distributed equally to both eyes, while the lines of the prisms coincide, but the bases of the prisms are located in opposite directions.

Aniseikonia. A high degree of aniseikonia is considered an indication for iseikonic spectacle correction, which is carried out using specially designed glasses. Iseikonic glasses use the principle of telescopic systems. Two lenses are placed in front of each eye - positive and negative. In one case, the positive lens is located closer to the eye, in the other - the negative one. In the first case, a direct telescopic system is formed, in the other - a reverse one. In this way, it is possible to achieve approximately equal size of perceived objects.

However, at present, iseikonic glasses are used extremely rarely, since modern possibilities of contact and surgical correction of refractive errors make it possible to compensate for high degrees of anisometropia.

Criteria for optimal selection of spectacle correction:

High visual acuity:

Full functions of binocular vision;

Refractive balance determined using the duochromium test;

Good tolerance, visual comfort.

The main advantages of spectacle correction:

Availability;

No complications;

Possibility of changing the power of spectacle lenses;

Reversibility of the effect.

Main disadvantages:

Changing the size of the retinal image with high power lenses;

The presence of a prismatic effect on the peripheral part of spectacle lenses. The prismatic action of a positive spectacle lens leads to the appearance of ring-shaped scotomas and a narrowing of the visual field. A negative lens causes a doubling of the peripheral visual field;

The impossibility of complete correction of ametropia in cases of high degrees of anisometropia.

Alternative methods:

Contact correction of ametropia;

Keratorefractive surgeries.

The correct selection of glasses for vision is a very important point, since in the modern world glasses have become not only a necessity, but also a stylish accessory. When choosing, you should take into account not only medical indicators, but also how the model complements the overall image of a person. Choosing the right glasses so that they last a long time is an art, because you need to take into account many factors.

Selection of glasses for vision and its features

Glasses for different types of activities will differ in materials of manufacture, shape, and reliability. For work and everyday use, more attention should be paid to the thickness of the lenses, selection of the shape of the frame according to the type of face, and overall image. If glasses are used for outdoor activities, sports, or driving, then the main indicator will be their reliability, comfort, and safety.

Despite the differences in glasses according to methods of use, there are general rules for selecting glasses for vision:

Selecting frames according to face size. This means that they should not create optical distortions. It should be noted that when negative, the lenses make the eyes appear smaller than they actually appear. With a plus, on the contrary, they increase. An incorrectly selected frame can enhance this effect. If you are nearsighted, you need to choose larger frames; if you are farsighted, you need to choose thin, invisible ones.
When choosing frames, you should start from the oval of your face. Glasses should create contrast, but not completely follow the shape of the face.
Choice of material. The most popular are metal frames. They present a wide range and low prices. Unfortunately, metal is an allergenic material and often causes a reaction. When purchasing glasses, you should try on and try different options: metal, plastic, horn frames, which are right for you.
Glasses frames should not exceed the width of your cheekbones.
Glasses that cause discomfort are not suitable. The earhooks or nose pads should not press or leave marks. It is important that the glasses are not too wide and do not slide off the nose.
When purchasing a frame, it is important to check it for deformation. To do this, turn the frame and see how symmetrical all the lines are.
It is important that the selected frame does not touch the eyebrows with the upper line and the cheeks with the lower line. The contact indicates that this model is large.

Vision testing and lens selection

In case of poor vision, you should consult an ophthalmologist. He will conduct a study, make an accurate diagnosis and select glasses.

The main vision test is carried out using the Sitzev table. It is a table with lines of letters of different sizes. The patient is located at a distance of 5 meters from the table.

Closing each eye in turn, the person names the letters that the ophthalmologist points to. This determines the optical power for each eye. If the patient's vision differs from 1, he is offered a second test, but using corrective lenses.

The doctor sequentially selects the appropriate lens, first for one eye, then for the other. Finally, a general vision test is performed. It is allowed for vision in lenses to be within 0.9-1.

To obtain more accurate results, examine the fundus and identify other vision problems, a hardware test is used. The most common method is computer diagnostics of refraction.

It is necessary to accurately determine the degree of myopia or farsightedness, determine whether there is astigmatism, and calculate the curvature of the cornea. Based on the results of a computer study, you can choose contact lenses or glasses more correctly to achieve the maximum therapeutic effect.

How different diopter levels affect the choice

Unfortunately, visual acuity is not always the same in different eyes. This situation requires more careful study and proper selection of glasses.

How to select glasses if your eyes have different levels of vision? During diagnosis, the doctor will have to determine the acuity of first one eye, then the other. After this, lenses will be selected.

Lenses for each eye are selected separately. To do this, close one eye and change lenses, selecting diopters until vision becomes sharp. Then surgery is performed on the other eye. Finally, the patient looks at the table with both eyes and repeats the test.

If the difference in diopter values is not large, it is allowed to use the same lenses in both eyes. In this case, the doctor will rely on the patient’s personal feelings. Lenses should not cause discomfort or tension.

If the difference in diopters is large, then a complex prescription will be written, which indicates the parameters across a line for each eye separately. In this case, ready-made glasses from an optical shop will no longer be suitable. They must be ordered separately. The specialist will make the lenses and install them in the frame according to the prescription.

Different visual acuity in the eyes often indicates the presence of other diseases. This may be due to lens diseases, glaucoma, cataracts, and retinal detachment. Possible disturbances in the blood supply to the eyes.

Taking into account facial types

The shape of the frame can not only create a beautiful image, but also completely ruin the impression of a person. Taking this fact into account, corrective glasses are selected based on the individual characteristics of each person. In nature, faces are found in oval, elongated, square, diamond-shaped and triangular shapes.

Let's look at each:

An oval face is a classic. Any glasses look good on him. The only rule is that their width should not be much longer than the face.
Round faces are equal in size on all sides. This has its advantages, but also creates a number of difficulties. In such a situation, rectangular frames or ones with pointed edges are suitable. Such glasses should not have equal width and height. General tendencies: neatness and elongation.
An elongated rectangular face needs additional volume. Rectangular shapes and large arms are ideal for it. Butterfly glasses fit perfectly; they are distinguished by their raised outer edges. Don't try square shapes. They will make the face more massive and heavy.
A square face also has equal dimensions in width and height, but it is distinguished by massive shapes. It needs to be softened. Experts recommend choosing frames with thin, rounded lines. There should not be right angles. Oval thin glasses or a cat eye shape will look great.
A triangular face may have a point at the top or bottom. For each case, you should choose your own option. If the face has the shape of a triangle with the base at the bottom, then the best choice would be a butterfly or semi-rimless frame. For a heart-shaped face, opt for thin oval frames. Rounded models without a rim will also fit perfectly.
A diamond-shaped face is characterized by its widest line at the cheekbones. It has a narrow forehead and chin. Moreover, it has wide cheekbones. For this type, you should choose oval-shaped glasses with an extension at the top. Models with rounded glass will also look good.

Sometimes it is worth playing with contrasts and choosing a form that is not quite suitable. The image will be more vibrant.

Video

Correction rules for farsightedness

Farsightedness is a disease in which the patient clearly sees objects located at a distance, but visual disturbances are observed near. Most often, farsightedness occurs as a result of a shortened eyeball. This disease occurs in both adults and children.

To correct farsightedness, special glasses are used. Only a specialist can select them. Glasses and their choice have their own characteristics.

Glasses for farsightedness are used only for vision correction. They are not curative or preventative. The main task of glasses is to correct vision and restore its sharpness.
Farsightedness glasses are worn constantly only in cases of relatively poor distant vision. Also indicators for their use are eye discomfort, headache, tension of the eye muscles.
When choosing glasses, it is important to consider the working distance. It indicates how and at what distance the patient works with small objects. Depending on this, the glasses can be weaker or stronger.
It is important that the distance from the lens to the eye is approximately 12 mm. This indicator is considered optimal, otherwise glasses can be harmful to health.
If you plan to wear glasses constantly, you should choose a bifocal or progressive type. In them, the optical power of the lenses changes. In the progressive type, it increases from top to bottom; in the fibocal type, the lens is divided into two areas for distance and near.
To choose the right glasses, you need to wear them for at least half an hour.
For different types of work, glasses with different optical powers may be prescribed. They should be changed when changing activities.

Choosing for myopia

Myopia is a disease in which the patient complains of problems with distance vision. He cannot see clear outlines of objects at a great distance. At the same time, he distinguishes objects well close up.

In most cases, myopia occurs as a result of increased tension in the eye muscles, reading in poor lighting, or in the presence of heredity.

Depending on the diopter value, the doctor may prescribe glasses for constant use or only for reading and computer work. Wearing glasses intermittently is indicated for those with vision no more than -1.

The choice of glasses for myopia has its own characteristics.

The frame is selected depending on the quality of vision. In case of large diopters, it is recommended to take a wide frame. This shape will not only cover the thick edge of the glass, but will also ensure reliable fixation of the lens in the frame.
If the degree of myopia is low, then you can choose semi-rimless frames, rimless glasses and other shapes that are most suitable for a specific face type.
Lenses for myopia can be made of thin glass or modern plastic. They are thinner in the central part and thicker at the edges. These lenses make your eyes appear smaller.

Consequences of the wrong choice

Glasses for vision correction are not just an accessory that will complement your look. They are necessary to provide a therapeutic effect and enhance visual acuity. If the vision test and glasses selection are carried out incorrectly, then such glasses can negatively affect your health. For this reason, only an ophthalmologist should write a prescription for glasses.

If glasses are chosen incorrectly, the patient may experience rapid eye fatigue, increased fatigue, poor health, and worsened vision.

Negative consequences do not appear immediately; in some situations they accumulate gradually.

Among the most common consequences of incorrect selection of glasses are:

regular headaches;
feeling of nausea and dizziness;
reduced performance;
unstable emotional state;
blurred vision.

If one or more of these signs appear while using glasses, you should contact your doctor and have your vision tested again.

Types of glasses frames

The quality of use of glasses directly depends on the frame. If it is chosen correctly and looks good on the face, then such an accessory will not only correct the vision problem, but will also fit well into the overall image.

All frames are divided into several types according to the material from which they are made.

Rimless glasses. These glasses are lenses that are attached to the temples. This option is perfect for those who cannot decide on the shape or color of the frame. The lenses look invisible on the face. The main disadvantage is that they cannot be used with large diopters. With a strong minus or plus, the lenses are too thick and the design looks bulky.
Aluminum frame. This option is the most common on sale. Glasses can be in the form of a full rim or half of it. Typically, such frames look light and are thin. The most popular color is golden, although the whole range of colors is available for sale. Among the shortcomings is the fragility of the frame. If dropped, it may bend.
Horn frame. The horn frame in a modern interpretation is made of highly durable and safe plastic. Such glasses were popular not only in the last century. Now they are also coming back into fashion. These glasses are suitable for almost every face type. The colors are natural. Beige, golden, brown, black tones are common. They look quite cumbersome.
Plastic frame. Plastic has become widespread for the manufacture of glasses due to the ability to create a wide variety of shapes and shades. Aviator glasses, Lennon glasses, and semi-rimless frames are in fashion. Plastic is used not only in classic glasses, but also in frames for sports or driving glasses.

In addition to the material from which frames are made, they can be divided by shape.

If you have problems clearly seeing objects in the distance, cannot distinguish letters when reading at the usual distance, or get very tired when working in an office, then you need to check your visual acuity and choose glasses or replace the ones you use.

Where to check

To select glasses, you need to test your visual acuity and get a prescription for glasses. Today, visual acuity testing can be done: in the office of an optometrist in an optical salon, at an appointment with an ophthalmologist in a clinic, and using tests on the Internet, online.
Online vision testing is gaining popularity - there are many websites dedicated to vision where you will be asked to download various tests to your computer to test your vision at home. For example, you can download and print a table with Landolt rings, hang it on the wall and try to read the letters from a certain distance. Or set the size of the letters that are most clearly visible on the screen for each eye. These classes can be quite interesting, but will not help you understand what glasses you need. At home, using a homemade table or using a computer, it is possible to determine visual acuity only very approximately, since it is impossible to comply with all the conditions for conducting such tests: lighting level, contrast and size of characters, distance, etc. In addition, such studies of visual acuity are not allow you to find out which optical power lenses, spectacle or contact, will provide the clearest and most comfortable vision. Only a specialist can determine which lenses are needed by examining your refraction using a set of trial spectacle lenses.

An ophthalmologist at the clinic will determine visual acuity, but even if you have a prescription, it is worth double-checking this data in an optical salon. Eyeglass correction professionals often have to deal with customer complaints about the quality of vision in new glasses that match a prescription issued by another institution. In this case, the customer does not have the right to make any claims to the glasses manufacturers. Checking or rechecking visual acuity in an optometrist’s office will be the key to producing high-quality glasses, and companies often carry it out free of charge when you subsequently place an order with them. Currently, many optical salons have an office of an optometrist or ophthalmologist, equipped with modern diagnostic equipment.

How to prepare

No special preparation is required for the vision test. You just need to provide the specialist with complete information about your vision problems. Remember at what time they arise: first thing in the morning or after long work, in what situations you experience discomfort and what it is. Think about what types of activities you need glasses for: computer work, etc. If you already use glasses or contact lenses, take them with you so that the specialist can take their parameters into account when selecting new ones. You must also bring your previous prescription for glasses.

Before the visual acuity test begins, your eye doctor or optometrist will talk with you and ask questions to learn about you, your eyes, and your overall health. Be prepared to talk about common diseases, hereditary eye diseases, special risk factors for professional activities, medications taken, and allergies.
Remember that some medications can affect your vision, causing short-term or long-term side effects. Thus, non-steroidal anti-inflammatory drugs, antiarrhythmic drugs, antidepressants, neuroleptic drugs, calcium channel blockers, oral contraceptives, tranquilizers, psoriasis drugs, tetracycline, thiazide diuretics and some others help increase the photosensitivity of the organ of vision. A number of drugs sometimes cause changes in pupil size by affecting the light sensitivity of the eye - these are atropine and other anticholinergics, scopolamine, antibiotics (fluoroquinols and tetracyclines), anticonvulsants (phenytoin), antidepressants (selective serotonin reuptake inhibitors), antihistamines, central nervous system stimulants (amphetamines, cocaine), sedatives (benzodiazepines), drugs to prevent erectile dysfunction, phenothiazines.

Visual acuity test

Visual acuity is the ability of the eye to distinguish small details of an object from a certain distance. It changes depending on the light. Visual acuity can be different for each eye due to hereditary characteristics or acquired defects (myopia, farsightedness, astigmatism, and other deviations of the visual organ from the norm). In addition, visual acuity decreases with age. Testing visual acuity includes examining the ability of the eyes to distinguish details near and at great distances, the ability to distinguish colors, and studying the field of vision (determining its defects).
Many optometrist offices in optical salons are equipped with autorefkeratometers, which allow you to quickly determine objective refraction, which helps in selecting the necessary correction tools. However, these measurements cannot replace a prescription for glasses (See article ).

When checking distance visual acuity, special tables are used, which are viewed from a certain distance under standardized lighting. For adults, Golovin - Sivtsev tables with letter optotypes and Landolt rings are intended. To determine visual acuity in children, they use E. M. Orlova’s table, on which images of objects and animals serve as optotypes.

The tables consist of 12 rows of randomly arranged letters or signs of a certain size - optotypes. In each row the optotypes are the same size, but from the top row to the bottom they gradually become smaller. The size of optotypes changes in arithmetic regression: in the first ten rows, neighboring ones differ by 0.1 units of visual acuity, in the last two rows - by 0.5. When using the Golovin-Sivtsev table, visual acuity is determined from five meters. If the patient from this distance sees the details of the optotypes of the 10th row of the table, then his visual acuity is 1.0. At the end of each row of optotypes, under the symbol V, the visual acuity of the patient who read this row from five meters is indicated.
Distance visual acuity can also be tested using special devices - sign projectors. In this case, a set of letters or symbols of different sizes is projected onto a screen hanging on the wall. The patient is required to name the letters shown or identify the symbols.

Rules for testing visual acuity:
1. Visual acuity should be examined monocularly - separately for each eye. And always start from the right.
2. Both eyes of the patient should be open, one should be covered with a shield made of opaque material. In the absence of a shield, you can cover the eye with the palm (but not the fingers) of the patient. It is important not to press through the eyelids on the closed eye, as this may cause a temporary decrease in visual acuity. The shield or palm should be held vertically in front of the eye so that the possibility of intentional or unintentional peeking is excluded, and the light enters the open palpebral fissure from the side. It is unacceptable to squint when examining visual acuity; in case of myopia, this leads to increased visual acuity;

3. The study should be carried out with the head and eyelids in the correct position. You need to make sure that your head is not tilted to either shoulder, forward or backward, and not turned to the right or left.
4. It is necessary to take into account the time factor: during a routine check, the time for determining the optotype is 2-3 s, during control expert studies - 4-5 s;
5. Optopips should be shown in the table with a pointer, the end of which should be clearly visible, when working with a sign projector - a laser pointer;
6. You need to start checking by showing the breakdown of optotypes in the 10th row of the table and gradually move on to rows with larger characters. In children and patients with reduced visual acuity, it is permissible to start checking from the top, showing one sign at a time to the row where the patient made a mistake, and then return to the previous row. Visual acuity must be assessed using a series in which all signs were correctly named. One error is allowed in rows 3-6 and two errors in rows 7-10, errors are recorded in the check result record.
To test near vision, use a small card with several paragraphs of text printed on it. Each paragraph is written in letters of different sizes. The card is held at a distance of 33-35 cm. A patient with normal near vision should read a paragraph whose letter size corresponds to a visual acuity of 1.0.
If, as a result of the test, it is determined that visual acuity is below normal (visual acuity equal to 1.0 is taken as normal), then the ophthalmologist will then examine the reasons for this decrease and determine the patient’s refraction.

Refractive Study

Determining refraction using a set of trial lenses is the oldest method. It allows you to set the optical power of the lens, which, when placed in front of the eye, provides the highest visual acuity. The study consists of testing the quality of vision with diagnostic lenses of different optical powers. To do this, the patient usually puts on a special trial frame, into which different lenses are inserted one by one, depending on whether the refraction is positive or negative according to the autorefractometer.

If autorefractometry has not been carried out, then, by attaching weak plus and minus lenses, they find out in which case the vision has improved, and then select lenses of the appropriate sign. lenses Successively try lenses of increasing optical power until the maximum visual acuity for the eye is achieved. For myopia, a lens with minimal refractive power is prescribed, providing high visual acuity. With farsightedness, on the contrary, with maximum refractive power, at which visual acuity is the highest.
Then a visual acuity test is performed binocularly, that is, both eyes together. In this case, the visual acuity of each eye should be 0.9-1.0. And if the quality of vision is different, then the maximum permissible difference in the optical power of the prescribed lenses should be no more than 2-3 diopters, depending on the patient’s individual tolerance.
Identification of the type and degree of astigmatism consists in determining the spherical and astigmatic components of the correction, as well as the position of the axis of the astigmatic lens, which ensures maximum visual acuity. To determine astigmatism, so-called astigmatic figures are often used, and when using optotypes, crossed cylinders are used.

The research method is based on the uneven vision of lines of different orientations in astigmatic figures, or, as they are sometimes called, dials, with an astigmatic eye. These figures are used both to identify astigmatism and to determine its degree and the position of the main sections. Crossed cylinders are used mainly at the final stage of refraction research to clarify the degree of astigmatism and the position of its main sections, that is, the strength and direction of the axis of the correcting cylinder.
After installing the lenses in the trial frame, the patient should be allowed to stay in the trial frame for several minutes, read, and walk around to check the tolerance of the corrective lenses. The parameters of these lenses are indicated in the prescription for glasses or contact lenses.
Interpupillary distance measurement carried out after selecting the correction using a set of trial lenses or a phoropter. Usually the distance between the centers of the pupils is measured using a regular ruler or a special device - a pupilometer. In well-equipped ophthalmological offices, special electronic measuring systems are used that allow all the necessary lens centering parameters to be established with high accuracy. Incorrectly measured interpupillary distance will result in incorrect alignment of the lenses in the frame, which, in turn, can cause poor health under visual strain. The prescription indicates the interpupillary distance for both eyes, and if it is necessary to prescribe progressive or aspheric lenses, the monocular pupillary distance.

Field of view examination carried out to test peripheral vision. The field of view is the area that is visible from a certain direction of view. Objects in the center of the visual field are visible more clearly than those located in the periphery.
Color vision tests used to test the ability to distinguish colors. This test allows us to identify color blindness (color blindness) in patients with suspected retinal or optic nerve disease or with a hereditary predisposition to color blindness, that is, who have a family history of color blindness.

Other methods of studying refraction

The duochrome test is based on the phenomenon of chromatic aberration in the eye. It consists in the fact that short-wave rays (blue-green) are refracted more strongly than long-wave rays (red), and therefore the focus of blue-green rays is located closer to the cornea than the focus of red ones. Thus, the myopic eye sees more clearly in red light, and the hyperopic eye sees more clearly in green light.

The subject is shown a luminous display, the left half of which is colored green, and the right half is colored red. Both have symmetrical black optotypes. The subject with a selected lens is asked to indicate against which background the signs seem clearer or blacker to him: red or green.
If it is red, then the eye alignment is myopic and a negative lens of greater optical power should be installed in front of the eye, and a positive lens of lower optical power; if it is on a green background, then the eye setting is hypermetropic and you need to choose a weaker negative lens, and, on the contrary, a stronger positive lens.

Binocular vision study

The eye-covering test (cover test) allows you to detect obvious or hidden strabismus with a high probability. The patient sits opposite the specialist and looks intently, without blinking, at some distant object located behind him. In this case, the specialist covers either the patient’s right or left eye without intervals. If at the moment of opening (transferring the shutter to the other eye) neither eye makes movements, then, most likely, there is no strabismus; if movement is noted, then strabismus occurs: divergent - when moving towards the nose, or converging - in the direction of the ear.
In the case of obvious strabismus, when opening one eye (the leading one), both make a quick adjustment movement in one direction, and when opening the other eye (the squinting one), they remain motionless. Latent strabismus is characterized by slow movement of only the eye that opens.

Glasses prescription

After determining visual acuity, the ophthalmologist or optometrist writes a prescription for the manufacture of glasses, which indicates: the patient’s data, the functional purpose of the glasses (for distance, for reading, for constant wearing, etc.), the required optical power of spherical and, if necessary, cylindrical lenses (indicating the values of the cylinder axes), interpupillary distance.

All prescriptions written out should be saved, since if necessary, they can be used to determine how vision has changed over time.

The selection of glasses should be carried out by a qualified specialist. Incorrectly chosen glasses can cause constant eye fatigue, cause headaches, fatigue, and impaired performance.

Prepared by Olga Shcherbakova

Spectacle vision correction is a method of correcting vision using glasses. Products were invented in Italy in the 13th century.

In modern society, this is one of the most common correction methods: according to WHO about 30 percent The world's population has vision problems, and most of these people choose glasses.

Optical vision correction: what it is, how it happens

The essence of vision correction is that it corrects the optics of the eye, and light is focused on the retina.

In myopic people the image is created not on the retina, but in front of it, and therefore they see distant objects unclearly.

They need glasses with diverging lenses, through which light rays will be focused precisely on the retina, creating a clear image.

In farsighted people On the contrary, the eyes create an image behind the retina. And that's why they need collecting lenses.

It turns out that the lenses in glasses change the length of light rays so so that light is focused on the retina, thereby helping people with visual impairments to clearly see the world around them.

Indications

Spectacle vision correction is the correction of visual impairment using a special device - glasses. They are frames and lenses. A lens is an optical transparent body that refracts light rays.

Indications for the use of spectacle optics:

myopia(myopia) up to -30 diopters;
hypermetropia(farsightedness) up to +10 diopters;
all types of complex and mixed astigmatism(impaired eye sphericity) up to +/- 6 diopters;

heterophoria(hidden strabismus);
presbyopia(age-related farsightedness);
aniseikonia(a condition of the eye in which the sizes of visible objects are perceived with a significant difference);
childhood up to 13 years old;
amblyopia(low vision, often one eye);
anisometropia(with a refraction difference of no more than 2 dioptres);
inability to undergo surgical or laser correction of visual impairment due to contraindications or other reasons.

There are no significant contraindications. Unless glasses cannot be used in infancy, with certain mental illnesses and with individual intolerance. Glasses are also not suitable for people whose professional activities require a wide field of vision or take place in smoky rooms.

Types of spectacle lenses and their corrective orientation

Lenses are divided according to their shape: their correctional focus depends on this.

Spherical

One of the surfaces (or both) of these lenses is spherical. They are used for both myopia and farsightedness. In the first case, the surface is concave, and the lenses themselves are divergent. In the second version, the lenses are positive (or collective).

Photo 1. This is what a checkered piece of paper looks like when looking at it through a spherical (left) and aspherical (right) lens.

Cylindrical

This type of lens, one (or both) of the surfaces of which is cylindrical, used to correct astigmatism. In this disorder, light is focused both behind and in front of the retina. The cylindrical lens corrects this problem.

Prismatic

Glasses with prismatic lenses are prescribed with heterophoria.

In addition to the shape, lenses vary in thickness. Depending on the value of the refractive index, lenses are divided into mid-index, high-index, ultra-high-index And standard refractive index lenses. The higher the index, the thinner and less clearly the prismatic effect of the peripheral part of the spectacle glass.

Photo 2. The structure of a prismatic lens. It is a crescent thickened on one side.

Methods for diagnosing vision and selecting glasses

Before selecting products, the ophthalmologist conducts a number of studies:

determines visual acuity each eye;
conducts automatic refractometry;
determines the degree and type of ametropia based on a subjective method (determining maximum visual acuity using spectacle correction);
clarifies maximum visual acuity under diaphragm conditions;
conducts a trial wearing of spectacle optics within half an hour.

Children and people with amblyopia are also treated drug-induced cycloplegia to turn off accommodation and determine the degree and type of ametropia using subjective and objective methods.

Having completed the examination, the doctor issues a prescription with the required optical power of cylindrical or spherical lenses, interpupillary distance and the reason for selecting glasses.

Well-chosen glasses provide high visual acuity, full binocular vision functions, refractive balance, good tolerability and visual comfort.

Attention! Once a year You will need to undergo a new examination by an ophthalmologist to make sure that the glasses you are using are still suitable.

Pros and cons of wearing glasses, effectiveness of correction

Glasses have many advantages:

Their main advantage is accessibility. It is not difficult to purchase glasses with the required diopters and lens shapes even in the most remote corners of the country.
They are very easy to use. There is no addiction, no need to remember the rules of use.
If you don’t like the correction method with glasses, then There is always the opportunity to choose a more suitable option.
Products are suitable for children under 13 years of age, who, due to their age, have few correction options.

This method has the following disadvantages:

Glasses do not provide complete vision correction.
They limit peripheral vision, disrupt the stereoscopic effect and spatial perception.
Glasses, unlike soft lenses, are less convenient to use: they fog up, slide off the nose, and interfere with active sports.
Incorrectly selected optics affects your well-being: it can simply cause a headache, or can cause further deterioration of vision.

How to use black perforated glasses products?

Perforation glasses - products with lenses made of dark plastic with holes in them, arranged in a pseudo-chessboard order. Because of their structure, they provide the person using them with eye muscle training: the gaze automatically focuses, trying to see the object through the holes.

Indications and contraindications

with heavy eye strain, for example, people whose professional activities involve working on a computer;
for short-term correction myopia, hypermetropia, astigmatism;
for short-term vision correction with various opacities of the optical media of the eye (for example, the initial stage of cataracts or superficial corneal opacities);
with increased photophobia.

They have a number of contraindications:

glaucoma(disease caused by increased intraocular pressure);
nystagmus(involuntary oscillatory eye movements of high frequency).

Before use, consult an ophthalmologist:

for retinal diseases eyes;
with progressive myopia.

Appearance of optics

Perforated glasses consist of a metal or plastic frame into which thick black plastic plates are inserted instead of lenses. 1.2-1.5 millimeters with many holes diameter 1.2-1.5 millimeters. The number of the latter is not standardized and depends on the size of the plates.

Photo 3. Perforation glasses. They are a frame with black opaque lenses, in which there are many holes.

The holes are cone-shaped and arranged in a hexagonal pattern: the horizontal distance between their centers is 3 millimeters, and diagonally - 3.5 millimeters.

Reference. Some glasses models have cutout at the bottom of the lens: it allows nearsighted people to see up close.

Impact principle

A person wearing glasses with holes multiple images are focused on the retina of the eye. To make the image clearer, the ciliary muscles of the eye change the curvature of the lens. Thus, the muscles work every time the gaze moves from one object to another.

This is a device Provides continuous training to unused eye muscles, while simultaneously relaxing those who are overstressed. Wearing glasses not only trains muscles, but also improves metabolism in the tissues of the eye, slows down the process of loss of elasticity of the lens, thereby preventing cataracts and other eye diseases.

Currently, many people have a variety of vision problems. To perform high-quality vision correction, you will need glasses. In order for this device to perform high-quality correction, you will need to select glasses for your vision.

Choosing the right glasses for your vision

In this article, we tried to tell you how to choose glasses for your vision and told you all the details. After contacting an ophthalmologist, he will use special equipment that will help you select quality products.

Visual acuity test

To select the right glasses for your vision, you first need to determine the acuity. An autorefractometer will help you choose the optimal visual acuity indicators. It is not recommended to trust everything to the computer. An additional check must be carried out by a specialist.

It is important to know! It is unacceptable to order glasses only based on the results of a computer study.

You can also check your visual acuity using a table or using a special sign projector from a distance of 5m. Each eye must be tested individually. You need to start choosing glasses for vision from the right eye.

Then, using a special frame, specialists attach plus or minus lenses. The selection of glasses for vision in this case will depend on the indicators of the autorefractometer.

Visual acuity is an important parameter when choosing glasses

It is necessary to select lenses only sequentially. If you have a problem of myopia, then a lens is prescribed that will have minimal refractive power. In case of farsightedness, on the contrary, a lens with maximum performance will be selected. Visual acuity of both eyes must be 0.9-1.0.

Sometimes you may encounter a problem when the vision of the right and left eyes is different. The maximum permissible difference in diopters should in no case exceed 2-3 D. In this case, everything will depend on the patient’s individual tolerance. If a person has problems with myopia and farsightedness, then he may be prescribed.

Astigmatism correction

The most difficult task for every specialist is the selection of correction for astigmatism. The main difficulty is that it takes some getting used to. Accordingly, with high degrees of astigmatism, you may be prescribed weak lenses, and then their effect will gradually increase. Instead of a trial frame, a special attachment to an ophthalmological diagnostic complex - a phoropter - can be used.

Selection of astigmatism correction

When selecting glasses for vision, ophthalmologists use a special table to test near vision. The selection will be carried out according to the same rules as for the distance. If the patient wishes to be fitted with bifocal glasses, then vision will be tested for both distance and near vision. The optical power in this case should not exceed 2-3 D. Where can I get my eyes checked and choose glasses? This is a common question that almost every patient asks himself. Ophthalmologists or specialized centers where sales are carried out will be able to carry out the selection.

Pupillary distance measurement

After selecting the correction, specialists will begin to measure the interpupillary distance. Usually the distance is measured using a regular ruler. Naturally, today there is a certain technique that allows you to measure the distance between the pupils. As a rule, the distance at distance will be 2 mm greater than at near.

Determination of interpupillary distance

Glasses prescription

After checking all the necessary indicators, the ophthalmologist or optometrist will write a prescription, which will indicate:

Patient data.
Optical power of optical or cylindrical lenses.
Purpose of assigning points.

Optotypes are special tables that depict various symbols

In some cases, specialists may also indicate additional indicators. It is not recommended to throw away all prescriptions prescribed by a specialist. They are necessary so that in the future you can take a prescription and see how your vision has changed over a certain period. Incorrectly chosen glasses can cause a number of problems, so before choosing, consult only real professionals.

The price of a mistake

Sometimes you can encounter a problem when the choice of glasses for vision was made completely wrong. If you encounter a similar problem and continue to use glasses for vision, then the process of addiction will gradually begin. As a result, the body will try to compensate for optical distortions at the cost of eye fatigue. Accordingly, after just a few days of using such glasses, you may notice a headache, as well as further deterioration of vision.

Now you know exactly how to choose glasses for your vision. This process will not be difficult if you carefully study all the recommendations of specialists. We hope that this information was really useful and interesting.