Contact lenses in the treatment of astigmatism and myopia

With astigmatism, a person's vision deteriorates, he experiences constant headaches, and it can also lead to conjunctivitis or blepharitis. During the treatment of this disease, the meridian where changes in the refraction of light occurred is corrected. The most popular treatment method is cylindrical or toric lenses. The latter are considered the best because they have a special spherocylindrical shape, which provides different optical powers in both horizontal and vertical positions.

Incorrectly selected lenses to combat astigmatism can lead to visual impairment, so in this situation it is imperative to contact an experienced ophthalmologist. In this article we will talk about the choice of optical lenses, their features and wearing period.

Astigmatism - visual impairment

Astigmatism Source: oftalmika.com
Astigmatism is a visual impairment that results in blurry and unclear vision of surrounding objects. Quite often, astigmatism is accompanied by such types of visual impairment as myopia or farsightedness.

Many people, faced with this disease, practically do not feel any inconvenience or discomfort. However, we are talking only about a weak degree of astigmatism, which does not require urgent medical intervention and is practically not felt.

However, patients who have a high degree of the disease very often complain of rapid eye fatigue, a sharp decrease in visual acuity, frequent headaches, and double vision.

Without correction, astigmatism not only impairs vision, but also provokes headaches and discomfort in the eyes. Astigmatism therapy involves correcting the meridian in which the refraction of light has changed.

Astigmatism is a form of visual acuity impairment in which a point object is not reflected on the retina and, accordingly, is not perceived by us as an image of a point. With such a visual impairment, a person sees all objects unclearly, as if in a distorting mirror.

Actually, the word astigmatism itself, translated from Greek, means the absence of point focusing (a - negation, stigma - spot, point), and the word “toric” is equal in meaning to the word “astigmatic”, but is most often used specifically in relation to soft contact lenses.

Spectacle correction with cylindrical lenses is possible, but toric contact lenses are more preferable.

In addition to impaired visual acuity, uncorrected astigmatism inevitably causes such unpleasant symptoms as double vision, constant need to squint, fatigue, a feeling of pressure in the eyeballs and frequent severe headaches of “unexplained origin.”

In addition, people with uncorrected astigmatism face additional visual problems in conditions of insufficient visibility, which, for example, when driving in the evening or at night, can lead to tragic consequences.

In most cases, the correct selection of astigmatic glasses or toric contact lenses quickly, within a few days (or even hours), relieves the patient of all these troubles.

Degrees of the disease

Doctors distinguish three degrees of the disease: weak (up to 3 diopters), medium (from 3 to 6 diopters) and high (more than 6 diopters). In the first case, the disease is easily correctable, which can be done with laser therapy, correction with glasses or lenses.

In the second case - with a moderate degree of astigmatism - you need to seek help from glasses, contact lenses or surgery. With a high degree of astigmatism, severe changes occur in the cornea, so hard contact lenses should be used.

Correcting astigmatism with glasses

Unfortunately, astigmatism is quite common today. Doctors say that the disease at a certain stage of development is found in one third of the population on the planet, and it develops directly from birth. Some people get astigmatism as a result of damage, surgery, or eye trauma.

When a patient is farsighted or nearsighted, he most likely also has astigmatism. As a rule, it is at a mild stage and is not felt by a person, which means it does not need correction.

At the same time, ophthalmologists say: astigmatism needs timely treatment and correction . Otherwise, it threatens with decreased vision, strabismus and other related complications. If you suspect that you are suffering from this disease, be sure to consult a doctor.

Astigmatism can be corrected in several ways, and glasses are one of them.

Advantages of correction with glasses:

• Availability.
• Economical.
• Easy to replace.
• Ease of use.

What is the difference between astigmatic glasses and glasses that correct other vision defects? What glasses lenses are currently offered?

The difference between astigmatic glasses and others

If conventional spherical lenses are used to correct myopia, then special astigmatic lenses . Their surface is unevenly curved, due to which different areas of the lens have a certain level of refraction.

Astigmatic lenses are a type of cylindrical lens. Separate negative and positive.

To understand what cylindrical lenses are, let's give an example. Imagine some kind of cylinder, for example, a metal tank for bulk items. Then mentally cut it lengthwise. Now imagine that the walls of the tank are transparent. You will see two cylindrical lenses - both positive. To get negative lenses, you need to make a cast of the cylinder.

The cylindrical shape of the lenses has an axis - an inactive meridian, where the direction does not exhibit optical properties. The direction of the axis that is perpendicular to the given one has the focus. The power of this lens is measured in diopters. Used to correct mild astigmatism.

If complex or combined astigmatism is diagnosed, toric lenses , which are a combination of spherical and cylindrical. They have the property of refracting light rays in the direction of two meridians, with each direction having its own optical power.

Optical power is determined in toric lenses using two indicators.

1. Optical power of the strongest meridian;
2. Optical power of the weakest meridian.

There are collecting (both meridians are positive) and mixed (one is positive, the other is negative).

Material for making astigmatic lenses for glasses

As in the manufacture of other glasses lenses, astigmatic lenses use either mineral materials (glass) or organic materials (plastics). Choose the material that you think suits you best.

People often lean towards plastic , a safe, lightweight and modern material. However, lenses made from plastic can be easily scratched.

Glass is more difficult to scratch, but it has a high refractive index, which makes it possible to make thinner lenses based on them. In addition, glass protects the visual organs from infrared radiation. However, glass lenses may break. And if this happens, there is a high probability of eye injury. Therefore, glass is rarely used for making lenses.

How to choose lens coating?

Ophthalmologists say that astigmatic lenses must be protected with an anti-reflex or anti-reflective coating, which reduces the amount of light reflected from the surface of the lens. Due to this coating, the eyes become much less tired, which is typical for people suffering from astigmatism.

If you decide to purchase plastic lenses, be sure to pay attention to the hardening coating. A good option is also combined coatings that combine both hardening and anti-reflective coatings, as well as other coating options.

For people who want not only to correct their vision, but also to protect their eyes from strong lighting, lenses for glasses with a tinted coating are made. In this case, tinting comes with different intensities (from 12 to 98%), different colors (gray, brown, yellow, pink, etc., each color for a specific task).

All of these lenses can, of course, protect your eyes from harmful UV rays and strong light. It is unlikely that you will order a large number of astigmatic glasses for yourself - due to the long production time and high cost. If your only glasses are both prescription and sunglasses, this can lead to certain problems. For example, these glasses will be uncomfortable indoors. Thus, it should be noted that it will rarely be comfortable to wear these glasses - only in the conditions for which you selected the color shade of the lenses.

Other lens options for glasses

If you really need lenses to correct astigmatism to help you see better and also provide reliable protection, then you should pay attention to photochromic glasses. Their difference is that they have the ability to change the level of darkness, taking into account where you are indoors or outdoors and how much light falls on them. The secret is in a special substance found in the lenses, which changes properties under the influence of light rays.

Thus, it turns out that when you go outside, transparent regular glasses immediately darken, and when you go indoors, they become transparent, which is quite convenient.

Polarized lenses can help protect your visual organs from the negative effects of glare and UV radiation, as well as from fatigue . This is quite relevant for active people who spend a lot of time driving a car, on the water, in the mountains. It must be said that this coating is quite expensive, it will significantly increase the cost of astigmatic lenses for glasses.

Conclusion

Lenses for the correction of astigmatism are selected by oculists especially carefully, since unsuitable glasses can cause headaches, high eye fatigue and other unpleasant symptoms. They are made individually, taking into account the needs of each specific person, this takes a certain period of time. They are more expensive than simple lenses that correct farsightedness or nearsightedness.

It is better when your astigmatic glasses lenses are coated with a strengthening and anti-reflex coating. This will extend the life of the glasses and make wearing them more comfortable.

You can also now order lenses with tinted coatings of varying degrees of protection and different colors. In addition, lenses with polarized coating and photochromic lenses are manufactured. At your request, you can equip your glasses with these types of optics.

How to treat?

Approximately 30% of patients with various ocular refractive errors also have astigmatism greater than 0.75 diopters. From a correction point of view, astigmatism is considered the most severe refractive vision pathology.

In this case, spectacle correction is ineffective, since in most cases it is difficult to tolerate by patients. The reason for this is various side effects of using spectacle lenses (prismatic, aniseikonic).

The difference in refractive forces along the main meridians of the eye and between the eyes, which almost always occurs with astigmatism, often causes aniseikonia and anisoaccommodation. Also, the prismatic effect of the spectacle system can provoke the occurrence of anisophoria.

The advantage of contact lenses in this case will be the ability to form a single lens-eye system. The lens repeats all movements of the eyeball, excluding the above-mentioned negative effects. For this reason, contact correction is the best way to treat astigmatism.

What is astigmatism and its types

Pathology is called clinical refraction, which is accompanied by a difference in refraction along 2 main meridians. In this condition, the image does not focus on the retina, resulting in blurred vision.

There are several types of astigmatism:

1. Simple – the presence of emmetropia in one of the main meridians.
2. Complex – clinical refraction has one sign.
3. Mixed – there is different clinical refraction in the main meridians.

Manifestations of astigmatism are not very specific. In the early stages, the pathology is characterized by slight blurring of vision. Patients are concerned about eye fatigue and loss of clarity in vision. Objects seem deformed, blurry, and uneven to them.

Individuals with astigmatism complain of eye pain, redness, and burning. They may experience double vision, especially with intense visual load.

Most often, symptoms of refractive error appear in preschool or early school age. The child confuses similar letters and swaps them in words. Quite often, young patients experience headaches and discomfort in the superciliary area.

A characteristic sign of astigmatism is a symptom of visual fatigue. When there is excessive strain on the eyes, a feeling of sand and dryness appears. There may be intolerance to the use of spectacle correction.

Can I wear contact lenses if I have astigmatism?

Source: Linza.Guru
Not so long ago, people suffering from astigmatism did not have much choice in terms of vision correction. More than 90% of patients chose glasses because the only alternative was uncomfortable hard contact lenses. However, we remember that glasses, despite their simplicity, have disadvantages that often turn out to be critical:

• change a person's appearance;
• may break or break at the most inopportune moment;
• fog up in the open air at subzero temperatures;
• limit peripheral vision;
• exclude many activities.

In addition, with severe astigmatism, glasses are poorly tolerated.

These days, patients with astigmatism have a choice. Leading manufacturers of contact correction products have created special astigmatic soft contact lenses. The lenses have a special toric surface that can correct astigmatism.

Their toric surface can be either on the front or back side. Such models of contact lenses can correct lenticular astigmatism up to 4.5 diopters, and corneal astigmatism up to 6.0 diopters.

The most common method of correction for astigmatism is glasses with special cylindrical lenses. According to statistics from leading ophthalmological companies, up to 80% of people with astigmatism choose glasses as a method of vision correction.

Points can be both positive (plus) and negative (minus). Plus or minus lenses for glasses are selected depending on the type of astigmatism. With high degrees of astigmatism, glasses are poorly tolerated - dizziness, eye pain, and fatigue may occur.

Often, cylindrical lenses to correct astigmatism are combined with lenses to correct nearsightedness or farsightedness that is present at the same time as astigmatism. It is quite difficult to select complex glasses and only a highly qualified specialist can do this.

Important!

Incorrectly chosen glasses can cause constant eye fatigue and poor vision. Despite the fact that glasses remain the simplest method of correction today, they have many disadvantages.

Glasses not only change a person’s appearance, break, or fog up at the most inopportune moment, but there are also medical aspects to this problem. In addition, glasses limit peripheral vision and often distort the size and shape of objects.

In addition to glasses, contact lenses are used to correct astigmatism. Some time ago, people with astigmatism did not have the opportunity to wear soft contact lenses - correction of astigmatism was only possible with the help of hard contact lenses.

Contact lenses with an anterior toric surface can correct corneal and lenticular astigmatism up to 4.5 D. Contact lenses with a posterior toric surface can correct corneal astigmatism up to 6.0 D.

How to choose

In order to select the optimal structure of lenses necessary for impaired perception of objects, you must first consult with an ophthalmologist. Buying glasses on your own will lead to a deterioration in the patient’s health, headaches and decreased visual acuity.

After the initial examination, the doctor will prescribe the following diagnostic measures:

• checking visual acuity, for which special tables are used, according to which a person tells what letters he sees;
• fundus examination to examine the retina and lens;
• using an autorefractometer to study the passage of a light beam through the internal structure of the eyes;
• Ultrasound of the organs of vision;
• corneal examination;
• measurement of intraocular pressure.

Only after carrying out diagnostic measures can the doctor determine what thickness the lenses should be and the material of manufacture.

Choosing lenses for glasses

For nearsightedness or farsightedness, stigmatic glasses are used. With their help, the light beam is coordinated in the center and directed through the pupil into the retina.

If the patient has a violation of the passage of the light beam, use 2 types of glasses.

• Cylindrical glasses for astigmatism. They are used when light perception is impaired in only one meridian.
• Toric glasses. They are used for impaired light perception in both meridians.

This is the basic structure of glasses; at the patient’s request, additional functions can be selected for them:

• reduction in thickness using polymer glass, which maintains functionality;
• chameleon glasses, which darken in the sun and lighten in the shade, which helps reduce eye strain from bright light;
• the use of durable materials that do not break upon impact;
• no glare formation.

Frame selection

When selecting glasses, you can choose the cheapest frame, but this will mean that wearing comfort is reduced.

For a certain surcharge, you can order a special frame that will meet the following criteria:

• the frame should extend along the entire perimeter of the lens, as this facilitates the correct passage of the light beam through the model;
• the frame for the lenses should be medium, not large and not wide, as this can cause distortion of perception at the edges;
• in case of illness, it is necessary that the edges of the glasses are at the level of the temples;
• The bottom of the frame should be higher than the bottom line of the nostrils.

Rules for selecting lenses

Fortunately for anyone who suffers from astigmatism, recent developments in science and medicine have led to the creation of special contact lenses called toric lenses. Such lenses should only be selected by a specialist, so do not self-medicate under any circumstances.

Fitting toric lenses is much more difficult than traditional lenses for vision correction, so this should only be done by a qualified doctor. If someone you know uses toric lenses from a particular company and strongly recommends trying this particular brand, don’t rush.

No matter how good the lenses may be for one patient, they may not suit (and even harm) another. If you have already selected astigmatic glasses for personal use, the procedure for selecting lenses will not raise any questions for you, since the algorithm of actions is almost the same.

Important!

Astigmatism lenses are thicker than regular lenses, so it is highly desirable that the patient can easily tolerate them during use. Also, due to their thickness, they transmit oxygen less well, therefore, it is imperative to adhere to the basic rules for their care and use.

Otherwise, complications may begin, including oxygen starvation of the eyes. But this problem has been solved by modern silicone hydrogel materials, which are several times better at oxygen permeability than conventional hydrogel materials. However, please note that toric lenses must be removed at night.

However, in addition to the disadvantages, lenses for astigmatism have a number of advantages that even toric glasses do not have.

Benefits of contact correction

The advantage of contact correction of astigmatism is that lenses can provide better visual acuity than glasses. This is due to the lack of vertex distance (the distance between the eyeball and the lens, which is 12 mm when wearing glasses).

Contact lenses form a single optical system, joining the cornea, and therefore require less optical power than glasses.

Another advantage of contact correction is that when using lenses, the size of the image on the retina will not change, which cannot be said about glasses. Contact lenses allow you to achieve maximum effect even with a large difference in refraction between the eyes.

Astigmatism of 1.5 diopters can be corrected with conventional spherical lenses. This is possible due to the fact that tear fluid, falling between the lens and the cornea, levels the surface of the latter.

Most often, rigid gas-permeable optical systems are prescribed for astigmatism. Unlike soft lenses, hard lenses can maintain their shape and stable position on the cornea, providing clear visual function. The disadvantage of hard lenses is the long period of adaptation.

When treating astigmatism, soft and hard toric lenses can be used. Pathology above 3 diopters is recommended to be corrected with rigid optical systems. These are most often made to order according to an individual design.

The adaptation period to hard lenses is much longer, since they are less comfortable to use. Also, image clarity sometimes decreases when blinking causes the lens to move off center.

Soft toric lenses are less mobile and therefore improve visual perception. They are more comfortable and therefore require less time to get used to. Recently, new technologies, materials and design solutions have emerged that have made soft toric lenses the best at correcting astigmatism.

A vision correction device is placed directly on the eye by a person suffering from the pathology.

Their advantages:

1. Convenient
2. Functional
3. Do not fog up
4. They can't be broken
5. Reduce eye fatigue
6. Indispensable for disorders of light refraction in the organ
7. Used for astigmatism, farsightedness, including age-related, and myopia
8. High corneal astigmatism can be corrected with contact lenses
9. when using contact lenses, the change in the field of view and the image of the object on the retina is minimal
10. contact lenses allow you to create optimal conditions for binocular vision, that is, vision with two eyes
11. contact lenses minimize optical aberrations and the prismatic effect that is characteristic of spectacle lenses.

Glasses and contact lenses are the most common methods for correcting astigmatism. However, both glasses and contact lenses only temporarily compensate for visual defects, but do not eliminate astigmatism.

Pros and cons of astigmatic glasses

The most popular method of correcting astigmatism is wearing special glasses, which help improve the quality of vision and also cope with the underlying problem. At the initial stage of the development of the disease, this method can be completely cured. Glasses for astigmatism have the following advantages:

• easy to use;
• inexpensive;
• it is possible to replace the optics;
• large selection of accessories.

But this correction method also has some disadvantages. In advanced forms of astigmatism, especially in old age, eyepiece intolerance is possible, which is expressed by the following symptoms:

• migraine;
• dizziness;
• pain and stinging in the eyes;
• violation of coordination in space.

Difficulties often arise during the adaptation stage. You can ask your doctor about how to get used to a new device. If the glasses were chosen correctly, then the unpleasant symptoms quickly disappear. The disadvantage of complex lenses is that they significantly limit peripheral vision and reduce the overall field of view.

If astigmatism is combined with myopia, then a violation of the proportions of objects is possible.

Features of the selection of children's optics

Source: HumanSenses.ru
The correct prescription of contact lenses for a child depends on the quality of the diagnosis, which includes various studies.

• Visometry – assessment of general visual acuity. If deviations are identified, corrective lenses are used, with the help of which the doctor tries to achieve a “one”. This study is basic and gives a general idea of ​​the clinical picture.
• Skiascopy is an assessment of the degree of a defect and the selection of the optical power necessary to correct it.
• Refractometry is used instead of (sometimes together with) skiascopy. It is distinguished by high reliability of results.

Based on the studies, the doctor decides on the possibility of using contact optics to correct astigmatism.

Important!

In some cases, biomicroscopy may be prescribed to identify infectious and inflammatory processes in eye tissue. If contraindications are found, the use of contact lenses is prohibited.

Selecting lenses for astigmatism begins with determining the required optical power, which will eliminate the negative effect of myopia (nearsightedness) or hypermetropia (farsightedness), which almost always accompanies astigmatism.

The astigmatic correction power determines the actual degree of the defect, and it is calculated from the results of skiascopy or refractometry. Also, the inclination of the meridian is determined, which is subject to correction.

In addition, the doctor needs to calculate the size of the cornea and the radius of curvature - the lens must exactly fit the child's eye. The prescription is completed by selecting a design, that is, a method for stabilizing the optics on the cornea.

Which ones are suitable for children?

It is believed that contact lenses for astigmatism are not prescribed to children. In most cases, this is associated with various kinds of misconceptions - the impossibility of fixing CLs, insufficient development of the eye, poor physiological tolerance of foreign objects.

But since contact lenses today are considered the most effective way to correct a defect, they should be used in cases where the doctor sees no contraindications. Another thing is that optics should be prescribed by an ophthalmologist based on objective evidence from the studies performed.

The main criterion for choosing suitable corrective optics for astigmatism in a child is the ease of use of CLs. A little earlier, children were prescribed exclusively hard contact lenses. But with the advent of hydrogel and, a little later, silicone hydrogel materials, soft ones are increasingly being prescribed to children.

Moreover, toric contact lenses are not always prescribed - if astigmatism is detected in time, and the deterioration in visual acuity has not reached 1.0-1.25 D, conventional spherical contact lenses made of vapor- and gas-permeable materials are prescribed.

In cases where a child’s vision has deteriorated by more than 1.5 D, only toric contact lenses are prescribed, which fully compensate for the defect.

Another aspect of choice is how long you will wear the optic kit. Contact lenses are recommended for children:

1. frequent scheduled replacement - suitable for middle and high school students who can track the time of use of contact lenses (7-14 days), as well as care for them;
2. planned replacement - convenient for elementary school students, since rare replacement (every 1-3 months, depending on the manufacturer) will shift the “burden of responsibility” to parents, and children at this age are able to take care of optics independently;
3. daily - will be the best option for children of any age who will be able to put on optics on their own.

In the first few months, parents should supervise their child's use of contact lenses. Children, due to the characteristics of their psychological development, cannot always pay due attention to their health.

The doctor decides which lenses to choose for a child with astigmatism, but he will definitely ask whether the child is able to care for the optics, put on contact lenses independently and track the replacement time. Depending on the age and parents' answers, a suitable kit will be selected.

Design or stabilization

Unlike adults, who often lead a sedentary lifestyle, children are restless. Accordingly, contact lens stabilization must take this factor into account. Children up to high school age are not recommended to wear stabilized TCLs:

• prismatic ballast - the lens takes the required position under the influence of gravity, which means that when the head is tilted, the cylindrical part of the optics will shift, which is unacceptable;
• truncation - a lens “standing” on the lower eyelid can fall out during active movements.

Changing the curvature of the torus will also not always be the optimal method of stabilization, since active movements of the child can lead to spontaneous loss of the optics.

The most optimal stabilization methods for children will be those that will ensure a reliable fit of the optics to the cornea and prevent its spontaneous loss.

1. Periballast - thinned parts of the lens are inserted under the eyelids, so the TCL is tightly pressed to the cornea, and thereby securely fixed in the desired position. However, not all children can get used to periballastic contact lenses, since they create the effect of excessive pressure on the eyes.
2. ASD - accelerated stabilization design, developed by Johnson & Johnson, has an X-shaped arrangement of stabilization sections. Their fixation and stabilization does not depend on gravitational influence;
3. Precision Balance 8/4 Design is an innovation from Air Optix that ensures the constant restoration of the correct position of the TCL on the cornea with every blink. Easily withstands the active movements of the child, which ensures constant correction of the location of the optics.

In addition to stabilized toric contact lenses, in some cases, doctors decide to use night contact lenses, which provide a therapeutic effect during the day, although they are used only during sleep.

What should you pay attention to?

Children's visual organs develop as they grow older, which means periodic visits to the ophthalmologist to check visual acuity are strictly necessary. With favorable correction and compliance with all medical recommendations, there is a chance that astigmatism will be “forgotten” by adulthood.

However, optics must change over time, because changing visual acuity (in any direction) requires changing the optical power of contact lenses.

Do not forget that CLs are not a complete replacement for spectacle optics. Glasses should be at hand when the child removes the lenses and right up to the moment when he puts them on again:

• from the moment you wake up and perform hygiene procedures, while the lenses are not yet put on, the glasses will be more comfortable;
• in the evening, when lenses worn during the day begin to cause eye fatigue;
• on weekends, especially if you do not plan to leave the house and be active.

The key to successful use of toric contact lenses is teaching your child how to care for the lenses. For lenses of planned and private planned replacement, the care rules are reduced to ensuring proper storage conditions during the period of non-use of TCL, as well as antiseptic treatment.

Daily contact lenses do not require the creation of special conditions, and it is enough for the child to remember which lenses to put on the left and right eyes, and after use, do not forget about the need to dispose of them.

Differences between hard and soft types

Source: en.ppt-online.org
Most often, hard lenses are made of polymers that have good permeability, which allows the cornea to “breathe”. Gas permeability is the main advantage of hard lenses over soft ones, since even silicone hydrogels do not provide the same permeability.

The second advantage of rigid optical systems is a stable position. Due to their rigidity, such lenses hold their shape well and provide stable correction. Hard lenses also last longer.

The disadvantages of such lenses are a long adaptation period and a high risk of intolerance. However, despite this, until recently, correction of astigmatism was carried out exclusively with the help of hard contact lenses.

Soft optical systems provide less gas permeability and stability, but such correction is better tolerated by patients. This is ensured by the fact that the back surface of the lens is able to follow the shape of the cornea and does not cause discomfort.

However, this same ability interferes with the patient, since the lens repeats not only the shape, but also all the surface irregularities. Thus, the lack of rigidity does not allow for maximum visual acuity.

Also, the surface of a soft lens can dry out, causing its optical properties to deteriorate. This necessitates the need to regularly moisten the lenses with drops.

Advantages and disadvantages of toric lenses for astigmatism

Toric lenses differ from all others in their special shape. Conventional optical systems have a spherical shape, while toric ones have a spherocylindrical structure, which allows the lens to provide different optical powers in horizontal and vertical positions.

This feature of toric lenses makes it possible to simultaneously correct astigmatism and refractive pathology (myopia, farsightedness).

Most often, toric lenses are recommended for astigmatism, which occurs due to differences in the curvature of the cornea or lens.

A toric lens has two optical powers, which are located in two sections. To minimize the intersection area, the lenses are equipped with stabilizing devices. Modern toric lenses allow for a stable axis position, which provides the most stable vision.

Indications for wearing toric lenses:

1. astigmatism from 0.75 diopters and above;
2. dissatisfaction with glasses with sphero-cylindrical or spherical lenses;
3. dissatisfaction with spherical lenses.

The peculiarity of astigmatism is that the curvature creates a difference in the refraction of the vertical and horizontal planes of the eye. The person begins to notice blurred vision, the inability to distinguish small details, sometimes vertical lines seem tilted to the patient.

• The eyes quickly adapt to toric lenses, as a result of which adaptation occurs quickly, painlessly and without any inconvenience.
• Astigmatic lenses have different wearing periods, among which you can choose the most suitable option for yourself.
• Like any other lenses, toric lenses can be worn while dancing, swimming, windsurfing, scuba diving, in general, using them like regular lenses.
• The field of view in lenses for astigmatism is not limited.
• The lenses do not cause discomfort, are not felt on the eyes and provide maximum comfort while wearing.
• If all operating rules are followed, they are completely harmless to health.
• By choosing toric lenses, you care not only about the health of your eyes, but also about their beauty.

Disadvantages of Toric Lenses

1. Like all contact lenses, toric lenses require proper and careful care; you must learn how to put them on and remove them correctly.
2. Improper use leads to inflammatory processes, so safety rules should never be neglected.

Toric lenses are produced by all leading manufacturers: Ciba Vision, Cooper Vision, Baush & Lomb, Johnson & Johnson

Whether or not to use toric lenses is a decision between you and your doctor. However, a wide variety of contact lenses can give you the ability to see the world around you clearly without surgery or laser correction, the effects of which are not yet fully understood.

Characteristics of glasses for astigmatism

With astigmatism, there is no single focus of the image on the retina.
Correction using special glasses is the most common method for astigmatism. Unlike ordinary “minus” and “plus” glasses (for farsightedness and myopia, respectively), in which the refraction of light rays occurs with the same force in any of their sections, the structure of cylindrical astigmatic glasses is more complex.

They refract light only along one of the axes - where there is astigmatism of the cornea. And since very often it is combined with other vision problems - farsightedness or myopia - the lenses of the glasses must correct these defects accordingly.

Therefore, when writing a prescription for corrective cylindrical glasses, the doctor must note the following characteristics:

• Sph (sphere) is the optical power of the base glass (expressed in diopters). Usually stands with a “+” sign, indicating farsightedness, or “-” - indicating myopia;
• Cyl is the sign of the cylinder and an indicator of the optical power of the lenses (also in diopters);
• AX is the cylinder axis (its exact location on the Tabot scale).

Feature of toric optics

Source: bolvglazah.ru
Toric optical systems are made from the same materials as spherical ones. Toric ones differ only in their special design. The modern market offers soft hydrogel and silicone hydrogel toric lenses for different wearing modes.

It is also possible to purchase colored and tinted lenses, as well as multifocal ones for the treatment of age-related farsightedness.

Such lenses have a spherocylindrical shape, which allows two optical powers to be provided in one lens. One value helps to correct astigmatism in the desired section, and the other is intended to correct concomitant refractive pathologies.

Important!

The indisputable advantage of a toric lens is a special fixation mechanism that holds the system in a stable position, providing clear vision when blinking, moving the eyeballs and head.

The fixation mechanism is very important, since the toric lens must occupy a certain position so that the action of the components is directed to the desired areas of the cornea.

Spherical lenses have the same refractive power throughout their entire length, and therefore can rotate across the surface of the eye.

Toric lens stabilization mechanisms:

• Prismatic ballast. The lens is thickened at the bottom, and under the influence of gravity it is fixed in the desired position. The disadvantage of this mechanism is also gravity: when the position of the body changes, the lens moves.
• Cutting off (truncation). Cutting off a segment at the bottom of the lens, which allows you to fix it with a cut on the edge of the eyelid.
• Periballast. The lens is thinned at the top and bottom so that the edges can be fixed under the eyelids. The eyelids will hold the lens in the required position.
• Change in curvature. By changing the curvature of the front or back surface, it can be ensured that it is positioned correctly. Optimal stabilization of the system can only be achieved by combining different stabilization mechanisms.

Laser marks allow you to determine the correct fit of the lens on the eyeball. The number of tags and their location will differ in products from different manufacturers.

If, after following all the rules, the lens still moves, the ophthalmologist can recalculate the axis so that when displaced, the components affect the desired segments of the cornea. Modern lenses can effectively correct disorders of up to 4 diopters.

How to choose TLC for vision correction?

It is better to entrust the choice of contact lenses to an experienced ophthalmologist. Based on the results of diagnosing the disorder, the doctor will be able to write a prescription for lenses that are suitable for a particular patient. It must be remembered that an incorrectly selected optical system will aggravate visual impairment.

Proper selection is very important when it comes to toric lenses. Since correct orientation is important for them, it is necessary to ensure that the lens is positioned correctly in the eye. To do this, manufacturers endow lenses with different properties and characteristics that help them stay in the desired position (thickness, truncation, etc.).

What to do when selecting contact lenses:

1. Determine visual acuity.
2. Determine objective and subjective refraction.
3. Get examined to select lenses. The examination includes keratometry, biomicroscopy, eye examination, and tear production testing. The doctor prescribes other tests as necessary.
4. Calculate the parameters of a toric lens, taking into account the vertex correction.
5. Try on trial lenses and evaluate vision using the optical system.
6. Assess lens fit.
7. Determine the position of the orientation marks.
8. Assess rotational stability, visual comfort and subjective sensations.
9. Learn to put on and remove lenses.
10. Remember the rules for wearing lenses, as well as the principles of caring for them.

Selecting toric lenses takes much more time than selecting a conventional optical system. This is due to the fact that in addition to standard tests, it is necessary to select cylindrical and spherical components, clarify the axes of the pathology, evaluate the position of the lenses, and sometimes even recalculate the axes.

The price of such optical systems also increases due to the complexity of their production. However, doctors argue that price in this matter is of secondary importance, because soft toric lenses provide high-quality vision and effective correction of astigmatism.

Toric contact lenses are recognized as the most effective method for correcting vision defects that occur with astigmatism. Lenses are more convenient to use, they provide stable fixation and good vision.

In terms of speed of adaptation, toric lenses have an obvious advantage over spectacle correction of astigmatism, since people very quickly get used to lenses of this type and more easily tolerate full correction.

Doctors know that when determining refraction (the degree of vision distortion), they should never use an old glasses prescription, since this prescription may not have been written for full, but for tolerable spectacle correction.

Wearing Features

So, the man turned to an ophthalmologist, and he, in turn, after conducting a series of studies, established an accurate diagnosis and determined a number of parameters that allowed him to find out what lenses the patient would need to correct the quality of vision. But lenses that are effective for both myopia and astigmatism have their own specific characteristics. So, having become the proud owner of this correction tool, it is worth remembering that putting on toric lenses is somewhat more difficult than ordinary soft ones. The fact is that they must be in the correct position on the cornea - the so-called meridians of the eye must coincide with a number of meridians of the products themselves. A lens, when put on correctly and in its intended place, will not move or interfere with the eye.

Rules for wearing lenses

On a note! It was possible to ensure that the lens “sits” on the eyeball as it should be thanks to some thickening of its lower part.

Also, at first, you should not hope that wearing lenses will be possible without discomfort, especially if a correction device (at least glasses) has not been used since childhood. You will have to get used to it gradually, that is, start wearing it for a short time at first, increasing the period of wear every day. Usually addiction lasts about a week.

Contact lenses are the best option for vision correction. They are ideal for those people who do not like to wear glasses, they have a big “minus”

Attention! If the discomfort does not go away within a week, then it is important to consult a doctor to select another means of correction.