Curvature of the cornea of ​​​​the eye treatment. Possible causes of keratoconus. Symptoms and stages of keratoconus

The term keratoconus comes from two Greek words: "kerato", meaning "cornea" in translation, and "konos" - "cone". Keratoconus is a degenerative eye disease in which the cornea becomes thinner due to structural changes and takes on a conical shape as opposed to the normal spherical shape. This pathology usually occurs in adolescence, but sometimes also occurs in children and young people under 30 years of age. The change in the shape of the cornea occurs slowly, usually over several years. However, there are also cases of more rapid progression of keratoconus.

The earliest references to keratoconus belong to the German doctor B. Mohort (dating back to 1748) and Taylor (1766), but for the first time the disease was described in detail and isolated from the group of other corneal ectasias by the British D. Nottingham in 1854. At that time, the treatment of keratoconus was reduced to cauterization of the cone-shaped part of the cornea with silver nitrate and the application of a tight bandage in combination with the instillation of drugs that cause miosis.

In 1888, the French ophthalmologist Eugène Kalt began work on a glass sheath designed to flatten the steep conical apex of the cornea and thereby correct its shape. This is the first known use of contact lenses to correct keratoconus.

Symptoms

The first signs of keratoconus are often the need for frequent shift glasses and blurred vision, not corrected by them. classic symptom this disease is the emergence of a set imaginary images known as monocular polyopia. This effect is most noticeable when viewing high-contrast visual patterns, such as a bright dot on a dark background. Instead of seeing a single dot, the eye with keratoconus sees a chaotic picture of many of its images.

The reasons

Despite extensive research, the etiology of keratoconus remains unknown. Presumably, this disease has several causes. Among them: genetic predisposition, stress, corneal trauma, cellular factors and environmental influences. All of them can serve as an impetus for the development of keratoconus.

Classification of keratoconus

According to the magnitude of the curvature of the cornea, the following types of keratoconus are distinguished:
- light (less than 45 diopters)
- medium (from 45 to 52 diopters)
- developed (from 52 to 62 diopters)
- heavy (more than 62 diopters)
The morphological classification is based on differences in the shape of the cone:
- mastoid - has a small size (up to 5 mm) and is located closer to the center of the cornea
- oval - 5-6 mm in size, usually displaced downward from the center
- spherical - dimensions exceed 6 mm, in pathological process more than 75% of the cornea is involved.

The advanced stage of keratoconus can sometimes progress to corneal dropsy, also called "acute keratoconus", when fluid enters the stroma through breaks in the Descemet's membrane, which leads to its edema and, it is possible, to secondary severe scarring of the cornea.

Diagnosis of keratoconus

With the technical improvement of medical equipment used for topographic mapping and measurement of the cornea, it has become much easier for ophthalmologists to diagnose keratoconus and choose more effective methods treatment.

Often, keratoconus is difficult to detect in the early stages, since vision is still slightly affected. One of early signs that cause alertness in an ophthalmologist is the difficulty of achieving maximum visual acuity in a patient even with ideal spectacle correction.

Other clinical manifestations that help confirm the presence of keratoconus are: thinning of the corneal stroma, deposits of iron oxide (hemosiderin) in the basal layer of the epithelium (Fleischer's ring) and tears in the Bowman's membrane. All of them can be identified by examination with a slit lamp. In addition, the presence of keratoconus is determined using instruments such as a retinoscope and a keratometer. They make it possible to identify signs of an irregular shape of the cornea.

Ultrasound and other pachymetry methods are certainly useful in confirming the diagnosis of keratoconus, as they are used to measure the extent of corneal thinning in patients suspected of having the disease. The equipment of some manufacturers, in particular, Bausch & Lomb and Orbscan, combines the capabilities various techniques conducting these examinations in order to more accurately establish the diagnosis.

Treatment of keratoconus

Not currently known medical preparations leading to regression or prevention of the development of keratoconus, but patients have the opportunity to slow the progression of the disease by refraining from rubbing the eyes. In cases where glasses or soft contact lenses are no longer effective, conservative (hard contact lenses) and surgical methods of treatment are used, including penetrating and layered keratoplasty, implantation of intrastromal corneal rings, epikeratophakia, asymmetric radial keratotomy, corneal collagen crosslinking.

Contact lenses for keratoconus

Refractive error
with keratoconus

Keratoconus correction
contact lens

In the early stages of keratoconus, the distortion of visual images is corrected with glasses that correct the slight myopia and astigmatism that are caused by the disease. In the advanced stage, contact lenses are the first choice for vision correction. In most cases, the mode of wearing them is permanent. There is no single lens design that is ideal for every type and stage of keratoconus. Required individual approach to each patient in order to make a carefully considered decision on the use of certain contact lenses, allowing you to achieve the best combination of visual acuity, comfort and condition of the cornea.

Soft contact lenses
The possibility of using soft contact lenses is limited due to the fact that such a lens, covering the wrong surface of the cornea, takes its shape. At the same time, a space filled with lacrimal fluid is not created between them, which, in turn, does not contribute to an increase in the efficiency of the refractive surface of the cornea in comparison with the initial one in keratoconus.

Rigid gas permeable contact lenses
Rigid gas permeable contact lenses are the main method of vision correction in keratoconus. They correct the irregular shape of the cornea and, together with the tear film that fills the space between the contact lens and outer surface cornea, function as the new refractive surface in the eye. The term "rigid" defines the type of lens, while "gas permeable" describes the properties of its material. There are many various models hard contact lenses.

"Double layer" lenses
Combined "two-layer" lenses can be used in difficult cases, for example - with individual intolerance to rigid gas-permeable contact lenses, severe central corneal opacities in keratoconus, thinning of the apex or recurrent epithelial erosion. This system consists of a hard lens mounted on top of a soft lens. Its goal is to maintain visual acuity by using a single lens that combines the benefits of two types of lenses.

Hybrid lens system
Contact lenses Softperm (Ciba Vision) belong to a hybrid lens system and are rigid gas permeable lenses with a soft hydrophilic edge. They are usually used in cases of individual intolerance to hard lenses. Softperm lenses have many advantages. They provide greater comfort than rigid gas permeable lenses, better centering on the eye and acceptable visual acuity. But these lenses are usually used only in exceptional cases due to the risk of induced corneal edema and neovascularization.

The main disadvantages of Softperm lenses are frequent breakdowns, the development of giant papillary conjunctivitis and peripheral corneal neovascularization. It should be noted that this type of lens was originally intended for the treatment of normal-shaped corneas rather than keratoconus. But due to the fact that these lenses provide the comfort of wearing soft lenses and visual acuity, as in hard ones, patients with keratoconus began to use them, who inevitably exceeded the recommended wearing periods, which eventually led to complications.

Scleral lenses
These are large-diameter lenses that rest on the white outer shell of the eye, called the sclera, while completely covering the cornea. Their size may seem intimidating, but there are many benefits to wearing them. Due to the size, scleral lenses do not fall out of the eye, and dust and dirt particles cannot get under them during wearing. These lenses are very comfortable to wear, as their edges are hidden under the edges of the upper and lower eyelids, making them invisible.

Crosslinking

Crosslinking is a new method to stop the progression of keratoconus. The full name is: "corneal collagen crosslinking with riboflavin (abbreviated as C3R/CCL/CXL)". This is a procedure that stiffens the cornea, allowing it to resist further deformation.

With keratoconus, the cornea weakens, becomes thinner, its shape becomes more convex, with the development of irregular astigmatism. Crosslinking enhances the bonds between collagen microfibrils in the cornea and between and within the molecules that form these microfibrils. This is achieved by using the non-toxic substance riboflavin (vitamin B2), which acts as a photosensitizer. Dosed ultraviolet irradiation in the long-wave range (UV-A) causes the formation free radicals inside the cornea and, as a result, chemical cross-links ("cross-links").

In practice, the crosslinking procedure is simple and gentle for the patient. Local anesthetic drops are instilled into the eye before removal of the corneal epithelium in the central part. Riboflavin solution is used to saturate the stroma for 30 minutes before ultraviolet irradiation, which is also carried out for 30 minutes using a precisely calibrated instrument, such as a UV-X system. Postoperative care is almost the same as after excimer laser photorefractive keratotomy, and includes wearing a therapeutic contact lens, as well as topical treatment for the next 3 days to increase comfort and accelerate epithelialization.

An increase in the number of bonds between collagen fibrils in the cornea gives it a rigidity similar to that observed during natural aging. The biomechanical strength of the human cornea can be increased by 2-3 times. This increased rigidity is thought to be responsible for slowing down or stopping corneal ectasia.

The crosslinking technique using a riboflavin solution in combination with exposure to ultraviolet radiation in the long wave range was developed in Germany in 1993, and the first operation using this technique was carried out in 1998. It has been steadily gaining momentum since the results became available. clinical research ongoing in several centers around the world, and the FDA recently approved a study on crosslinking.

Published data unequivocally show no progression of keratoconus over a 3-5 year period after the procedure. For example, in the Dresden study, 60 eyes after crosslinking for 5 years did not observe further development process, and more than half of them showed some flattening of the cornea by up to 2.87 diopters. A slight improvement in visual acuity was also revealed: with optimal correction — by 1.4 lines.

Potential candidates for crosslinking are those who have progression of keratoconus or other keratoectasia (transparent marginal corneal degeneration, iatrogenic cases). For surgery, the thickness of the cornea must be at least 400 microns to protect the endothelium from potentially toxic ultraviolet (UV-A) radiation at an index of 8 after removal of the epithelium. This parameter is measured prior to treatment: if the cornea is too thin, a hypertonic riboflavin solution may be applied to induce sufficient swelling to safely carry out the procedure. During the use of this method, no dangerous side effects were identified.

It is important to understand that collagen cross-linking is not a panacea for the treatment of keratoconus, but rather aims to stop the progression of this disease. After the procedure, patients will continue to wear glasses or contact lenses, although the prescription may need to be changed. The main goal of crosslinking is to stop the progression of keratoconus and thus prevent further deterioration of vision and the need for corneal transplantation.

Radial keratotomy in the treatment of keratoconus

This type surgical intervention is not generally accepted, and reliable data on its safety and effectiveness at present. The opinions of ophthalmologists, as well as the available research results on this issue, are contradictory. Those few who perform it speak of the effectiveness of the technique: it combines not only stabilizing properties in relation to the progression of keratoconus, but also refractive, correcting ametropia and improving visual acuity. Unfortunately, adequate research on different reasons is not possible, therefore, it is necessary to consider this technique experimental.

The following are options for performing keratotomy for keratoconus.

Asymmetric radial keratotomy
The “mini” technique of asymmetric radial keratotomy (ARK) is sometimes identified with its predecessor, radial keratotomy, which is not entirely true. This is a special surgical procedure, in which micro-incisions are made on the cornea in such a way as to smooth out or enhance the irregularity of the shape of the cornea.

The beginning of the technique was laid many years ago, and the person who provided greatest influence its development was the outstanding Russian ophthalmologist Svyatoslav Fedorov, the father of modern radial keratotomy.

Professor Massimo Lombardi, who studied with Fedorov for a long time, developed the technique and adapted it specifically for the treatment of keratoconus. After many years of testing and technical improvements, an asymmetric "mini" surgical technique was developed. The "Fedorov" radial keratotomy had to be adapted to deal with the variability in the shape of the cornea in each case and the unevenness of its thickness, characteristic of keratoconus. For this reason, the incisions were shortened and limited to the central optical zone.

The procedure is individual for each patient and requires a careful assessment of the indications for it and a preoperative examination. The cornea is carefully scanned and mapped in detail. After perimetry and other examinations, it is calculated where, to what depth, what length, at what angle, etc. every cut will be made. This outpatient procedure is performed under local anesthesia and lasts 1-3 minutes on one eye.

The experience of the surgeon plays a very important role in performing this manipulation, since it takes many years to learn how to use this method for the treatment of keratoconus. For this reason, ARC is not widespread. According to the author, the fact that the treatment of a patient with keratoconus is selected taking into account a specific, individual in each case, corneal profile, makes it possible to obtain optimal results from this surgical intervention.

Optical diamond surgery
The technique of optical diamond surgery developed by academician Artsybashev, according to the author, makes it possible to maintain the stability of the results even 20 years after the operation. It not only stops the progression of keratoconus, but also improves visual acuity. The incisions made by this method in keratoconus due to the redistribution of intraocular pressure exerted on the corneal tissue lead to a change in its irregular shape and, as a result, to partial or full recovery functions. After surgery, in most cases, the cornea is completely restored, visual acuity increases. This method is used to preserve the patient's own cornea and prevent acute keratoconus requiring corneal transplantation or keratoplasty.

The operation is performed on an outpatient basis, under local anesthesia and lasts 2-3 minutes. Patients are discharged from the hospital on the first day after surgery. Its results are felt the very next day. Patients are under medical supervision, control examinations are carried out one, three, six months, one and two years after the intervention. Also developed postoperative treatment, which provides conditions for better scarring of micro-incisions, thanks to which the basis for strengthening the cornea is created. Since 1983, Dr. Artsybashev has performed more than 1000 operations with I-IV stages keratoconus, and more than 30,000 refractive surgeries to improve the optical function of a healthy cornea. Each operation was planned taking into account the exact individual shape of the cornea, so a thorough preoperative examination is necessary.

In the end, I would like to remind you once again that all the described variants of keratomy are not included in any protocol for the treatment of keratoconus and cannot be recommended for use along with the generally accepted ones. The methods require full-fledged studies, based on the results of which a decision can be made to introduce them into global practice or a complete ban on these interventions in ophthalmology.

Intrastromal corneal rings

The newest surgical method correction of irregular astigmatism in keratoconus, an alternative to corneal transplantation is the implantation of intracorneal ring segments (keraring).

Two types of intrastromal rings are currently available: Intacs, which have a hexagonal section and are placed at a greater distance from the center than the second type, Ferrara Rings, which are shaped triangular prism. Rings can be implanted deep into the middle of the corneal substance (stroma). The operation is quick and painless, outpatient settings using anesthetic drops. In this case, a specially designed vacuum layered dissector is used, which creates an arc-shaped pocket for rings, or, according to the latest technology, a femtosecond laser. The exact mechanism of action of the rings is not known, but it is believed that they exert an outward buoyancy against the curvature of the cornea, flattening the apex of the cone and restoring it to a more natural shape. Previous studies also assign a large role in this process to the thickening of the overlying epithelium adjacent to the segments, which gives a significant leveling effect.

Ferrara Rings intrastromal corneal rings differ from Intacs in that they have a smaller radius of curvature (in the former it is fixed and is 2.5 mm, in the latter it can vary from 2.5 to 3.5 mm), and also in that, despite to a smaller size, the chance of glare after installation is less due to the prismatic shape. Any light beam that hits the ring is reflected in the opposite direction in such a way that it does not enter the field of view. Because Ferrara Rings are smaller and closer to the center of the cornea, they provide more strong effect and can correct myopia up to -12.0 D, i.e., more than can be corrected with Intacs rings. The appearance of glare was noted in some patients with a large pupil diameter. In such cases, installing Intacs is recommended.

As a rule, the results of treatment in most patients are positive, as evidenced by a significant decrease in the degree of astigmatism after surgical intervention, accompanied by an increase in visual acuity both with and without optimal spectacle correction. So far, the groups of patients studied for the most part remain small, however, the achievement of favorable outcomes within 24-36 months of follow-up is noted. top scores were obtained in eyes with mild to moderate keratoconus.

Perforation of the anterior chamber during surgery, lack of expected result, infection, aseptic keratitis, postoperative extrusion (pushing out) of the ring are on the list possible complications. Removing problematic segments can be easily done. This allows the cornea to return to its original preoperative state. Studies have shown that in about 10 percent of cases, it becomes necessary to remove the rings, either due to the complications listed above, or due to lack of effect. But this does not exclude the possibility of subsequent implementation of layered or penetrating keratoplasty.

Corneal transplant

Corneal transplantation, or keratoplasty, is a surgical intervention to remove damaged corneal tissue and replace it with a healthy one taken from the eye of a suitable donor. It can improve vision and relieve pain in an injured or diseased eye.

Keratoplasty is usually indicated in cases where the cornea has become severely deformed after treatment with other methods, or when it is damaged due to illness, infection, or injury.

Corneal transplantation involves the removal of part (layered keratoplasty) or all layers (penetrating keratoplasty) of clouded or deformed tissue and its replacement with a graft taken from a deceased donor.

Dr. Edvard Zirm performed the world's first successful human cornea transplant in 1905 in what is now the Czech Republic, and the graft remained viable for the rest of the patient's life. Since that time, a number of new techniques for this operation have been developed. The most common method of corneal transplantation is penetrating keratoplasty.

Keratoplasty (Penetrating Keratoplasty or Corneal Transplant)
Penetrating keratoplasty (see photo) includes complete removal cornea (all 5 layers) and its replacement with a donor one, which is sewn into place so that the distance between adjacent sutures is 20 microns (40% of the thickness of a human hair!).

The stitches are usually removed after a year. It may take the same amount of time to restore vision to a satisfactory level. Often, patients who have undergone penetrating keratoplasty need to wear glasses or contact lenses to correct their vision. The graft survival after this operation is on average 15 years.

Deep anterior laminar keratoplasty (DALK)
Such a surgical intervention is performed in cases where the endothelium lining the cornea from the inside is healthy, and the stroma is pathologically changed. The operation allows you to remove the affected stroma and preserve healthy underlying tissues of the deep layers. The pathologically altered anterior part of the cornea is removed and replaced with a new donor one, which is fixed with small sutures. The graft lies on top of the patient's own tissues lining the cornea from the inside. Since the inner layers of the graft do not move, the risk of rejection is lower, and the prognosis for long-term graft survival is better. However, the patient after a deep anterior layered keratoplasty waiting for a longer recovery period, in addition, the same quality of vision is not always achieved as with penetrating keratoplasty.

Risks in corneal transplantation

Corneal rejection
Rejection is the process by which the immune system The patient recognizes the donor cornea as foreign and forms an immune response against it. Such cases are very common and occur in every fifth patient who has undergone transplantation. Most rejections are suppressed effective treatment, the graft takes root and continues to function. The key to a successful outcome is early treatment. At the first appearance of symptoms of rejection, patients should consult a specialist as a matter of urgency. Symptoms to look out for include:
photophobia, or photophobia hypersensitivity to bright light)
irritation or pain;
redness;
decreased or blurred vision.
Treatment consists of instillation of steroid eye drops and, sometimes, orally or parenteral administration drugs in this group.

Infection
The surface of the graft may become infected if the sutures holding it in place have loosened or broken. In cases where the infection cannot be controlled, it can lead to death of the transplanted tissue or loss of the eye.

Glaucoma
This is an increase in intraocular pressure that damages the optic nerve at the back of the eye. Steroid drugs used after corneal transplantation may cause glaucoma in some patients.

Retinal disinsertion
It is observed in approximately 1% of patients after penetrating keratoplasty. Can be treated with subsequent surgery.

Keratoconus is a painful deviation of the eyes with a change in the structure of the cornea, which thins and curves under the influence of intraocular pressure. Deformation changes the shape of the cornea to a cone. The refraction of rays passing through the conical cornea becomes incorrect, distorting images and violating visual acuity. The disease is called keratoconus, which means "conical cornea" in Greek.

Keratoconus is most often diagnosed in adolescents during puberty. Quite rarely, keratoconus occurs in children and people over thirty years of age. The disease is fixed in 3-4 people per 100 inhabitants. Not later than 20 years after its manifestation, the disease stops developing. However, at very advanced cases possible rupture of the cornea and even loss of vision.

AT international classification diseases ICD-10 keratoconus has a code H18.6.

Classification

Keratoconus can be unilateral, when only one eye is affected, or bilateral. Statistics show that about 95% of all cases of the disease occur in both eyes at once.

• Primary, caused by genetic factors;
• Secondary, arising as a result of adverse effects of the external environment, surgical operations on the organs of vision, the consequences of injuries.

• Acute;
• chronic;
• with variable flow.

• Weak, with a value of up to 40 diopters. During this period, small morphological changes occur in the cornea of ​​the eye, signs of astigmatism appear;
• Average degree, no more than 55 diopters. Cracks in the Descemet's membrane of the cornea are formed, allowing moisture to pass from the anterior chamber. The top of the cone acquires a cloudy outline, and the patient practically ceases to see in the dark;
• Severe, with a diopter value of more than 55. Visually, the unnatural shape of the cornea is already noticeable, it can become completely cloudy. Vision deteriorates sharply, a person sees poorly even during the day. At high probability corneal rupture requires urgent surgery.

• Moderate, with its thickness close to 0.5 mm;
• Medium, with a value of 0.4–0.5 mm;
• Over or close to breaking, with a thickness of less than 0.4 mm.

• Dot dome. The pathology has a diameter of about 5 mm and is located in the center of the cornea;
• Oval shape of the dome. The cornea is protruded up to 6 mm, its deformation is localized below the center and sags;
• spherical deformation. The cone is more than 6 mm, the disease covers up to 70% of the cornea.

Causes of Keratoconus

Oddly enough, doctors have not yet come to a consensus about what causes the occurrence of keratoconus. Among the most common theories of occurrence are:

• hereditary or genetic predisposition;
• Negative consequences after laser vision correction;
• Unfavorable ecology, influence of ultraviolet radiation;
• The consequence of improper selection of contact lenses that cause injury to the cornea;
• Injury to the eye as a result of mechanical impact and even the habit of rubbing the eyes;
• Violations at work endocrine system, dysfunction hormonal background, failures in the process of metabolism.

According to another theory, it is believed that the cause of keratoconus is the consequences of previous infectious diseases, since in most cases it is formed in children with weak immunity. Some researchers associate the occurrence of keratoconus with mental trauma, stress and nervous experiences.

Symptoms of keratoconus

Initially, the symptoms of keratoconus are similar to other eye diseases. A person complains of severe eye fatigue, double images while looking at light objects on a dark background, the appearance of flies before the eyes, and the presence of discomfort. If the pathology development process begins to progress rapidly, visual acuity will decrease, as happens with myopia or astigmatism. In the early stages, wearing glasses or contact lenses helps to overcome visual impairment, in the future optical correction loses its effectiveness.

Vision in keratoconus decreases gradually. Due to the increase in the number of diopters, the patient often has to change glasses. However, this does not always guarantee a positive result. Pathology can sometimes progress so quickly that changing glasses does not have time to adjust vision. also cannot be of benefit due to abnormal corneal bulge. In this case, the patient should begin serious treatment of the organs of vision.

Usually, the stages of development of keratoconus continue for 10-15 years, sometimes it is delayed for a longer period of remission. Only in 5% of cases, the disease abruptly turns into an acute form, in which there is a rupture of the Descemet's membrane with leakage of intraocular fluid.

Diagnosis of keratoconus

The beginning of the detection of keratoconus of the eye is the moment the patient contacts an ophthalmologist with a complaint of visual impairment. After the interview, the doctor measures the visual acuity and refraction of the eyes. If the presence of myopia or hyperopia is not confirmed, the examination of the patient will be continued. Exist following methods diagnostics:

• Skiascopy. With the help of a special device (skiascope), a counter-movement of shadows specific to keratoconus, called the "scissors effect" is determined;
• Keratometry is the most common diagnostic method, which determines the curvature of the cornea;
• Refractometry. With the help of the technique, irregular astigmatism and myopia, which arose as a result of corneal deformities, are detected;
• Computed tomography of the eye or its ultrasound. These studies reveal changes in the tissues of the cornea, including scars on its surface.

On the late stages disease, its diagnosis is not difficult, since the pathology of the cornea is immediately visible without special devices. Only examinations will be required to determine the degree of damage to the eye tissue. When the diagnosis is confirmed, some additional examinations will be required in related specialists.

Treatment of keratoconus

Treatment of keratoconus of the eye with drugs, unfortunately, is not yet possible. Taufon and other similar drugs are designed to nourish the eye tissue and relieve burning and dryness in the visual organs. Therefore, such medicines can only be part of complex therapy when choosing a particular method of treatment.

In the initial stages of keratoconus, conservative methods of treatment are used. More severe forms keratoconus require surgical intervention. They also use traditional medicine.

Vision correction with glasses is prescribed first. While their application brings therapeutic effect contact lenses are not allowed. The reason is quite clear: the lenses are capable of causing microtrauma to the surface of the eye.

Only when the corneal taper situation changes the refraction of the image does the spectacle fitting stop. To replace this optical device lenses come, the selection of which occurs individually, taking into account the stage of the disease and the capabilities of the body:

• Soft lenses do not scratch the cornea, but their use can correct vision only with a slight protrusion. Practice shows that such lenses are not very suitable for keratoconus: taking the form of the cornea, they do not create a tear film, which is why the refractive power of the eye does not improve;
• Rigid lenses are made personally, so they have a great therapeutic effect. Retaining their shape, they are able to eliminate corneal curvature. A tear film can already form between these lenses and the eye. The disadvantage of lenses is to create uncomfortable sensations when worn on a damaged cornea;
• Hybrid lenses consist of a hard center and a soft rim, combining utility and comfort. Recommended for those who find it difficult to wear hard lenses.

The development of medicine has made it possible to develop several options for surgical correction, but only a doctor should make a choice in favor of a particular operation. by the most modern method it is considered the introduction of colorless rings into the cornea tissue (implantation of intrastromal rings), which will bring its shape closer to the natural one. Nevertheless, the operation is not able to stop the course of the disease.

The operation of the eye is modern and safe method treatment and has a short recovery period.

Also popular is the operation, in which donor tissue is placed in place of the damaged one. It is recommended for severe corneal deformation as a result of other methods of treatment, but carries the risk of such dangerous complications as glaucoma and rejection of the transplanted tissue. Finally, in the most advanced cases, a corneal transplant is used. This operation is the only way to stop the course of the disease. The most qualified clinic for the treatment of keratoconus is in Moscow.

Folk methods should be resorted to early stages disease in order to slow down the progression of pathology. It is possible to use traditional medicine during the rehabilitation period, but it must be understood that it is impossible to correct the cornea in such ways. But compresses prepared on the basis of chamomile flowers help relieve eye itching, relieve excessive tension from a sore spot.

Keratoconus and the army

"Do they take to the army with keratoconus?" - the question is very important and has a great social aspect, since, as mentioned earlier, keratoconus is a disease of the young, and its first signs may appear shortly before the call. It should immediately be noted that with such a disease they are not taken into the army. Moreover, if there is a suspicion of keratoconus of the eye, then the young man receives a deferment from conscription for six months. After a specified period of time, the diagnosis must either be confirmed or refuted.

In this situation, you need to clearly understand that any military registration and enlistment office has its own medical board, which assesses the health of the conscript, and only she has the right to decide whether the patient is fit for military service or not. Ordinary ophthalmologists cannot make such decisions for a commission.

Prevention of keratoconus

To minimize the occurrence of keratoconus, young people first of all need regular visits to the ophthalmologist and the implementation of all his recommendations. Upon detection inflammatory processes in the organs of vision, prompt measures should be taken to eliminate them.

While reading, working at a computer, while watching TV, it is necessary to control the load on the eyes. To prevent excessive stress it is necessary to provide sufficient lighting for the place of work or activities that require concentration and attention to the eyes.

Protective equipment should not be neglected under circumstances that can harm the eyes: dusty air, cold wind, bright light.

Proper nutrition and a lifestyle without bad habits will benefit the whole body and the eyes in particular. It is important to take prompt measures when allergic processes appear and observe eye hygiene by washing them with decoctions of healing plants.

Astigmatism is a disease in which the eye is unable to focus a clear image on the retina. The name of the disease comes from the Greek stigma, i.e. dot.

Causes and symptoms of the disease

Normally, a beam of light passing through the optical refractive media of the eye, the lens and the cornea, is focused on the retina in the form of a point. With astigmatism, due to the curvature of the surface of the cornea or lens, there are several focal points, and instead of a focal point, a focal line is formed. The more curved the surface of the cornea or lens, the longer the focal line will be and the higher the degree of astigmatism.

The disease is most often congenital, for the most part it is inherited. Acquired astigmatism can develop as a result of trauma or surgery on the cornea, as well as with keratoconus.

YOU SHOULD KNOW IT!

The shape of the eyeball in the vast majority of people is not perfectly spherical. Slight astigmatism up to 0.5 D is not noticeable and is considered physiological.

With a stronger degree, the disease negatively affects the ability to clearly see objects. Curvature of the surface of the cornea or lens is often combined with nearsightedness or farsightedness (myopic, hyperopic or mixed astigmatism).

You can suspect something is wrong when a person sees the objects surrounding him, distorted or not clear. Complements the picture of a headache that occurs with strain of vision, as well as a feeling of heaviness and pain in the eyes. If the disease is not treated, visual acuity may decrease over time.

YOU SHOULD KNOW IT!

A distinctive feature of astigmatism from other visual impairments is that the decrease in the clarity of perception of objects does not depend on their location in space.

To confirm the diagnosis, it will be necessary to undergo an examination by an ophthalmologist. According to the results computer diagnostics and examinations using cylindrical lenses, the doctor will be able to make a definitive diagnosis and recommend appropriate treatment.

Treatment

A radical improvement in visual acuity in the treatment of astigmatism can be achieved only by surgery, in other cases one should talk about vision correction.

In the past, complex glasses with cylindrical lenses were prescribed to correct vision in this disease. In addition to the fact that it was not easy to choose and make such glasses correctly, and the glasses themselves had to be changed regularly, for many patients wearing them caused headache, dizziness, pain in the eyes. Today it is possible to use special contact lenses for astigmatism, which are called toric. The decision on which correction method is right for you should be taken only after consultation with an ophthalmologist. In the process of vision correction, it will be necessary to systematically undergo an examination by a specialist, and change glasses or lenses in accordance with the changes that have occurred.

To correct astigmatism surgically, several methods are currently used, the choice of the most suitable of them is carried out by an ophthalmologist based on the results of a comprehensive examination of the patient.

The most modern and perfect method of surgical correction of visual acuity in astigmatism today is the method of excimer laser therapy. The essence of the technology of excimer laser vision correction is to model a new surface of the cornea of ​​the eye by removing part of it by the evaporation method. The advantages of the method are low invasiveness, painlessness, high accuracy of calculations and execution, less likelihood of complications.

Fix four circles in a row and look at the lines. Important: first check each eye separately, and then both together. You can take the test with or without glasses.

Do you see clear black lines in all circles?

Analysis of results

If the lines appear fuzzy in one or more directions, this may indicate various problems with the functioning of the eye. In this case, you should consult an ophthalmologist or optometrist. If you notice differences in lines even with glasses, you should have your glasses checked, as uncorrected astigmatism significantly reduces visual acuity.

Astigmatism is a curvature of the cornea or lens of the eye, as a result of which they do not have an even spherical shape. Due to the curvature of the cornea, a different refractive power appears in certain parts of the eye. As a result, the image on the retina is transmitted blurry, there are options when part of what is seen is fixed before the retina, and part behind the retina. With astigmatism, a person sees part of the image clearly, and part is blurry (variants are possible). Astigmatism is often accompanied by nearsightedness or farsightedness.

Depending on which part of the eye has a curvature of the sphere, lens and corneal astigmatism is distinguished. Since the cornea has a large refractive power, corneal astigmatism has a greater impact on the quality of vision than lens astigmatism. Astigmatism is measured in diopters.

There is congenital and acquired astigmatism. Congenital up to 0.5 diopters is noted in many children and does not have a special effect on the quality of vision, it is also called "functional". If congenital astigmatism exceeds 1 D, correction is performed using glasses.

Acquired astigmatism appears after injuries, surgery on the eyes (if mistakes were made during the operation).

To be sure of the diagnosis, you should go through full examination at the ophthalmologist. Many clinics today offer these types of examinations: visual acuity test, ultrasound inner eye, measurement of refraction, diagnosis of various pathologies, examination of the shape and refractive characteristics of the cornea, a comprehensive analysis of the state of the optic nerve and retina.

Treatment of astigmatism allows both conservative - lenses and glasses, and operational - laser correction or keratoplasty.

Glasses allow you to correct astigmatism already in childhood, the main task is to choose the right lenses, since cylindrical lenses are required for astigmatism. If the patient has a high degree of astigmatism, he may have headaches and pain in the eyes as a reaction of the body to wearing glasses. Therefore, it is very important to visit an ophthalmologist regularly and, if necessary, change glasses to strong or weak ones.

Contact lenses for astigmatism should be toric. These are soft contact lenses, on the area of ​​which a toric sphere is created. They allow you to correct astigmatism up to 4.5 - 6 diopters. Lenses have a number of advantages:

aesthetic: do not change appearance; practical: do not break, do not fog; medical: allow more accurate correction of corneal astigmatism, minimize optical aberrations characteristic of glasses.

However, sometimes in patients with prolonged wearing of lenses, deformation of the cornea is possible. Recovers when lenses are discarded former form. This should be taken into account when choosing toric contact lenses.

Laser correction (about 20 techniques) is the safest. But it also has limitations for application (it is not carried out when diabetes in severe form, glaucoma and high stages of cataract, with progressive myopia). As a method of treating astigmatism, laser correction has the following advantages:

minimal in time (the duration of the entire operation is up to 15 minutes, the effect of the laser is about 30-40 seconds); has a wide age range (from 18 to 45 years); used for various diagnoses; minimum recovery period and high level of safety.

It is important to remember that with astigmatism, treatment is prescribed and carried out only by a specialist after a thorough examination.

This disease is most often diagnosed in patients during puberty, its development can last for years, and in other cases it occurs and develops rapidly. Treatment of keratoconus in the initial stages is conservative, and in advanced cases, keratoplasty will be required.

Keratoconus is an eye disease in which the cornea becomes thinner, and a protrusion forms at the site of its greatest thinning. Gradually, it acquires the shape of a cone, the refraction of the eye changes, and a number of characteristic visual impairments and pain occur.

The disease is quite rare and doctors do not undertake to accurately name its cause for the time being.

At first, the disease keratoconus is difficult to diagnose, it is often mistaken for myopia or astigmatism due to reduced vision (myopia) and the occurrence of blurring of objects (astigmatism). However, here the resulting drop in vision is more rapid. With it, the patient often has to visit an ophthalmologist, since during the selection of glasses the condition worsens significantly, and the glasses can no longer provide proper correction. Usually, the correction is ineffective, and in the future, due to the curvature of the cornea, the patient cannot wear soft lenses.

Another sign of the diagnosis of "keratoconus" will be sharp drop in initial stage twilight vision. With further progression of the disease, the severity of the daytime worsens, gradually the patient (stage 5) sees only blurring of the contours of objects.

The most frequent and feature diseases - doubling of objects (monocular polyopia). This symptom directly points to keratoconus, and the symptoms will intensify as the disease progresses. At first, on a dark background, the patient sees only 2 imaginary objects instead of a real one, but as the disease progresses, the number of objects increases, their contours are blurred.

Keratoconus also causes severe burning in the eye and pain. If the patient often rubs his eyes, then the progression of the disease accelerates, and with it the pain intensifies.

Possible Causes of Keratoconus

Although exact reasons scientists cannot yet establish the occurrence of keratoconus, they name a number of factors that can provoke the disease, these are:

• Genetic predisposition: blue sclera syndrome, Leber's amaurosis, Ehlers-Danlos disease.
• The presence of frequent microtraumas of the cornea, for example, staying in a room contaminated with large dust particles.
• Some systemic diseases.
• Ultraviolet irradiation of the eye (often found in residents of the highlands).
• Errors in the selection of lenses.

Almost all causes of keratoconus are somehow related to the nutrition of the cornea of ​​the eye or the impact of third-party factors on it.

Types of keratoconus

Most frequent age the onset of the disease is 10-16 years. Development of the disease in other patients age groups quite rare (although last years diseases became more frequent). As a rule, keratoconus is first diagnosed in one eye, but later the disease captures both eyes.

According to the duration of the disease

The development of the disease can last for years (up to 15 years), while the stages of keratoconus will increase gradually and the detection of the disease may be delayed due to the blurring of symptoms. In other cases (about 50%), the disease develops in fits and starts. In this case, symptoms may appear, and then for a long time the disease seems to stop.

The most complex form of the disease is corneal dropsy - acute keratoconus of the eye (about 7% of patients). In this case, the thinned cornea ruptures, and the intraocular fluid flows out, forming cloudy spot on the eye. After 4-8 weeks, the cornea is scarred and there may be a partial improvement in vision, but the resulting scars are an obstacle to normal vision.

According to the severity of the disease

One of the most famous classifications of the disease is differentiation according to the degree of increase in symptoms. It involves dividing the entire period of the disease into degrees of keratoconus.

1. The initial stage (curvature less than 45 D) distinguishes 2 degrees of the disease, while ophthalmologists fix minor morphological changes, among which the most characteristic will be the visualization of nerve endings on the cornea. At the second stage, astigmatism and myopia are diagnosed, which are poorly corrected with glasses.
2. Grade 3 (curvature 45-52 D) is characterized by clouding of the top of the cone, the occurrence of cracks in the Descemet's membrane through which moisture enters the cornea from the anterior chamber. Cloudy spots appear on the cornea, and acute keratoconus may develop. The patient practically does not see at dusk.
3. At grade 4 (curvature 52-62 diopters), turbidity affects most cornea. There are disturbances in daytime vision. The sharpness drops significantly, an even greater number of cloud points appear. The bulge becomes visually noticeable.
4. For the 5th degree (curvature of more than 62 diopters), almost complete clouding of the cornea, a decrease in vision to 0.01–0.02 diopters, is characteristic. With this degree, there is a threat of perforation (rupture) of the cornea, which is dangerous for the loss of the eye. During this period, urgent surgical intervention is required.

Features of the diagnosis of keratoconus

At first, the diagnosis of the disease is difficult, but modern methods make it possible to establish its presence at almost any stage of the disease.

Diagnosis of keratoconus always begins with a visual acuity test (refractoscopy). The ophthalmologist notes during repeated visits unevenness (asymmetry) of refractive errors and irregular astigmatism.

Among instrumental techniques will be:

• Diaphanoscopy allows you to determine the wedge-shaped shadow on the iris.
• Skiascopy helps to detect irregular astigmatism (the presence of a "springy" shadow due to the displacement of media).
• Ophthalmometry makes it possible to detect cone-shaped changes in the cornea.
• Computer photokeratometry is a very informative examination that allows you to set a number of important parameters of keratoconus: angle, radius, the very conical shape of the formation in the early stages.
• Biomicroscopy of the eye allows you to explore non-inflammatory changes in the structure: nerve endings, rarefaction of the stroma, thickening, cracks, breaks.

In specialized ophthalmological clinics conduct such studies as optical and endothelial microscopy of the cornea.

Conducting a comprehensive examination allows you to prescribe adequate treatment keratoconus.

Conservative treatment of eye keratoconus

The first attempts to treat keratoconus date back to 1854. During this period, the British doctor D. Nottingham developed a technique for cauterizing the cornea with silver nitrate, after which a pressure bandage was applied to the eye. This treatment gave a good result, but did not stop the disease in all cases. And in 1888, Eugene Kalt (France) used glass to flatten keratoconus. It was the prototype of modern cross-linking.

Today, among the general prescriptions for all degrees of illness, there is treatment vitamin complexes, the use of mydriatics (mesotonin, midriacil), immunomodulators, antioxidants (taurine).

At 1 and 2 degrees, they carry out tissue therapy, injections of ATP, methylethylpyridinol (subconjunctival, parabulbar), physiotherapy (phonophoresis, magnetotherapy, etc.)

In the early stages, spectacle correction is used. Treatment with special lenses, they are soft at the edges and hard in the center (performs cone correction). Soft lenses are not suitable for grade 3 keratoconus due to the large curvature of the cornea.

Today, the technique of corneal cross-linking is widely practiced. Using special equipment, the epithelium is removed from the surface of the cornea, then riboflavin is instilled and the affected area is irradiated with UV rays. As a result, the cornea becomes more resistant to deformation, the disease stops, and it is often possible to achieve regression of the disease. This procedure is followed by soft contact lenses.

The excimer laser procedure (PRK + PTK) is also possible in the early stages, it allows you to correct astigmatism and strengthen the cornea.

In some cases, thermokeratoplasty is used. With the help of a coagulator, point applications are made that contribute to the flattening of the cornea.

Acute corneal keratoconus is treated with mydriatics, be sure to apply a pressure bandage (to prevent corneal perforation). Therapy acute form lasts at least 5-6 weeks.

Surgery and Keratoconus

Among the more radical methods of treatment is the correction of keratoconus with the help of a surgical operation. It is always shown at 4 and 5 degrees of the disease, while the method of implantation of corneal rings is used.

Stromal (corneal) rings are removed from the patient's eye, and donor rings - grafts - are placed in their place. This allows you to change (flatten) the surface of the cornea, stabilize it, and normalize refraction.

Engraftment is very high (about 99%) since the stroma has no blood vessels, the resumption of vision is observed in 100% of cases and allows you to have a vision within 0.8-1.

There are 2 methods of implantation: through ( complete replacement stroma) and layered (only a few layers are replaced).

Fully restore vision in keratoconus is possible only through surgery.

Possible Complications

Keratoconus disease provokes eye dropsy (acute keratoconus) in which the condition of the diseased eye worsens significantly and can lead to loss of the eye.

The treatment of this disease is long, and the obligatory result will be the formation of scars, which will significantly impair vision.

Prevention of the appearance of keratoconus of the eyes

Prevention of this ophthalmic disease consists in careful attitude to the eyes:

• The cornea should not be exposed to too intense UV irradiation, with bright sunlight It is advisable to wear sunglasses.
• The cornea must be protected from various microscopic damages: hitting small objects, when working in conditions with coarse dust, the eyes are protected with special glasses.
• You should not rub your eyes too often - this also provokes microtrauma.
• With a drop in visual acuity, it is imperative to contact the attending ophthalmologist for the selection of glasses.
• It is very important to choose the right contact lenses if they are needed.
• When diseases of the stroma occur, it is imperative to carry out adequate treatment.

Heal and be healthy!

toric
The term "toric" describes cylindrical or barrel-shaped objects or shapes. With astigmatism, the cornea and/or the lens of the eye are not perfectly spherical, resulting in blurry vision. Toric lenses can effectively compensate for astigmatic visual impairment.

Frequently asked questions about this page

What is myopia?

If you are nearsighted, you can see well without glasses at close range, but far away everything seems fuzzy and blurry. The most common cause It consists in an enlarged eyeball (axial myopia), in which the image is formed in front of the retina, as a result of which vision becomes blurry.
Like farsightedness, nearsightedness (myopia) is measured in diopters. Rodenstock minus lenses allow you to optimally compensate for this disturbance – and use your visual potential to its full potential.

What is EyeLT ® Rodenstock?

EyeLT ® is the short name for Eye Lens Technology, a patent-pending new lens technology from Rodenstock. Introduced in 2011, EyeLT ® technology has made it possible to achieve a goal that was previously considered impossible: up to 40% improvement in near vision in progressive lens wearers. This was a real milestone in the history of the development of progressive lens calculation technology.

To calculate lenses using EyeLT ® technology, an optician will perform one more measurement - an individual test for near vision. Eye parameters are measured automatically and with high accuracy using the DNEye ® scanner, an innovative measuring device. Together with the results of standard measurements, all this Additional Information fixed in a prescription and passed on to Rodenstock, where we create the best custom lenses for you. Thanks to them, you will be able to use your individual visual potential to 100%.

Yes! The size of the near zone is decisive for the comfort of reading with progressive lenses. Impression ® Progressive Lenses with EyeLT ® Technology have a particularly wide lens that guarantees unrestricted reading pleasure and clear vision at intermediate and long distances. This means that you will have a lot more options with progressive lenses than with simple glasses for reading. Whether it's near, far or intermediate vision, one pair of glasses is enough for all occasions.

How should glasses be stored?

While you are not wearing glasses, it is best to store them in a hard case. If you don't have one, just store them in a safe place with the lenses up.

How can I tell if I need progressive lenses?

Look at yourself while reading. If you have to hold a book or newspaper a long and uncomfortable distance from your face in order to see clearly, then you need glasses for close distances. This is where reading glasses can help. However, progressive lenses have the decisive advantage that you can only use one pair of glasses for different distances. This will allow you to always easily respond to Everyday life and see clearly in any situation.

Lenses from the Rodenstock Perfection category as the perfect solution: all visual system analyzed completely individually, which allows you to use your visual potential to the fullest.