Astigmatism is a violation of refraction, associated with the distortion of the shape of the cornea or lens of the eye. This visual disorder is the most common cause of poor vision in childhood and adolescence. Thus the person can be short-sighted, far-sighted or combine these infringements.What causes astigmatism? How is the correction of this violation carried out?
Content
1Definition of disease
2Causes
3Kinds
4Symptoms
5Possible complications
6Diagnostics
7Treatment
7.1Correction optics
7.2Laser and surgical correction
7.3Medicines
8Prevention
9Video
10conclusions
Definition of disease
Astigmatism is a disorder of eye refraction caused by an irregular shape of the cornea or lens.This violation leads to the fact that the light rays are scattered, as a result of which a distorted image is formed on the retina. Astigmatism more than 1 diopter is manifested by rapid fatigue of the organs of vision, vague visualization of objects, headache, discomfort in the superciliary area.
Along with myopia and hyperopia, ophthalmologists attribute astigmatism to conditions of ametropia, which are characterized by changes in the back focus of the eye and changes in the refractive properties of optical media.This disease among all types of ametropia occurs in 10% of cases.
Violation of the uniform curvature of the cornea or lens leads to the fact that their surface has a different refractive power in the two meridians.For this reason, the beam of rays does not converge at one point of the retina, as it does in a person with normal vision. Sometimes the image focuses on the retina (in the form of a blurred ellipse or "eight"); in other cases - before or behind the retina. A person with astigmatism sees the image distorted, diffuse, fuzzy.
Early correction of astigmatism is the key to successful prevention of strabismus and amblyopia.
Causes
There are 2 etiological varieties of astigmatism:
Congenital astigmatism;
Acquired astigmatism.
The first variant of the disease is caused by the genes that the children received from their parents. In the inheritance from the parents, the child got the wrong shape of the cornea. Somehow it is impossible to influence or prevent this natural fact.
People with the ideal shape of the cornea do not exist. Everyone has a minimal degree of astigmatism. If the degree of violation does not exceed, diopter, then in sight it does not affect in any way. This version of the norm is called physiological or functional astigmatism.
If astigmatism goes beyond the threshold of 5 dpt, then it has a significant effect on vision and requires spectacular correction already in early childhood.If you do not correct the child's astigmatism, then the development of a "lazy eye" (amblyopia) is possible, when the eye simply has not learned to see well.
Manifestation of amblyopia
Acquired astigmatism is caused by changes in the cornea as a result of external factors. The causes of acquired astigmatism:
Trauma or scar of the cornea;
Burn the cornea and conjunctiva;
Keratitis;
Keratoconus;
Dystrophy of the cornea;
Eye surgery on the sclera and cornea;
Sutures on sclera and cornea after operations;
Diseases of the eyelids.
Any violation of the structure of the cornea leads to a change in its optical properties. If even slightly changed its shape, immediately changes and refraction of the rays of light. A typical example: in the century a large barley formed that presses on the cornea and causes astigmatism, while the person does not understand why his vision has deteriorated.
Kinds
Refraction of the main meridians of the eye (perpendicular to the plane) determines the following types of astigmatism:
Direct astigmatism:the largest refractive force is observed in the vertical meridian;
Reverse astigmatism:The greatest refractive force is noted in the horizontal meridian;
Astigmatism caused by oblique axes.
In addition, distinguish between astigmatismcorrect and wrong. The first variant assumes mutual perpendicularity of the two main meridians, the wrong astigmatism is characterized by an oblique arrangement of meridians.
Correct astigmatism can be simple (one of the meridians has normal refraction), a complex (a vivid example is complex myopic astigmatism) or mixed (different refraction for both meridians).
The simultaneous combination of astigmatism with a disorder such as nearsightedness, characterizes myopic astigmatism, and tandem with hyperopia - hypermetropic astigmatism.
Due to the direction of the meridians, an astigmatic axis is formed, which is determined in degrees. The index of the difference in the refraction of the meridians is the magnitude of astigmatism, the value of which is determined in diopters. In accordance with this indicator, degrees of astigmatism are distinguished:
Weak degree(up to 3 diopters);
Average degree(3-6 diopters);
High degree(more than 6 diopters).
Also, corneal astigmatism is distinguished, in which there are defects in the refractive capacity of the cornea, and lens astigmatism, when violations are detected in the lens.
Congenital astigmatism with dioptric indices within, 5 is physiological and does not affect the visual acuity, therefore, does not require correction. Acquired astigmatism is always a pathology.
Symptoms
Astigmatism is most often manifested in preschool or primary education. A child with such a violation can confuse letters, complain about poor vision, fuzzy vision of objects, constant headaches, uncomfortable sensations in the superciliary area.
The manifestations of astigmatism are not very specific. In the initial stages, the disorder often manifests itself with a slight defocusing of the eyes and is often accepted by the patient as eye fatigue. To guard should such manifestations as:
Loss of vision(objects are seen as deformed, uneven, fuzzy);
Pain in the eyes;
Redness, burning;
Doubling with visual load(reading, working behind the computer screen);
Difficulty in visual determination of the distance to objects, etc.
In general, for any type of astigmatism, the following symptoms are characteristic:
Astenopia(rapid visual fatigue);
The feeling of "sand" in the eyes;
Difficulties in wearing glasses.
Possible complications
Astigmatism, which remains without correction, has a negative effect on the eyes, causing eye diseases (eg, conjunctivitis, blepharitis).In addition, this pathology causes poor health, dizziness, rapid fatigue.
Failure to correct for moderate to high astigmatism usually leads to the development of refractive amblyopia and strabismus. Especially it concerns children.
Diagnostics
If an astigmatism is suspected, the ophthalmologist performs a comprehensive assessment of the state of the organs of vision and their functions. Diagnosis can include such types of examinations as:
Inspection of eye structures;
Investigation of refraction;
Visometry (visual acuity check) without corrective optics and with correction;
Sciascopia with spherical and cylindrical lenses;
Refractometry;
Biomicroscopy of the eye;
Ophthalmoscopy;
Ophthalmometry;
Ultrasound of the eye;
Computer keratotopography.
Treatment
To treat astigmatism use optical, contact, laser and microsurgical correction.
Correction optics
Ophthalmic correction is performed by individual selection of complex glasses, in which spherical and cylindrical lenses are combined.The first of them is selected according to the norms of correction of hypermetropia or myopia, but the refractive power of the cylindrical lens is designed to coincide in terms with the degree of astigmatism.
Selection of glasses for astigmatism
With a high degree of astigmatism, the use of complex glasses can be accompanied by visual discomfort, dizziness, and sharpness in the eyes.
A modern alternative to spectacled correction of astigmatism is the use of toric contact lenses.The advantage of contact correction is that the lens with the eye forms a single optical system and, unlike the glasses, does not cause visual spatial distortions.
With a low degree of astigmatism, orthokeratological (night) lenses can be used.
Schematic representation of differences between the spherical and toric lens.
Both glasses and lenses are able only to correct the defects of vision for a while, but they can not completely rid themselves of astigmatism.
Laser and surgical correction
With intolerance of glasses, lenses, impossibility of performing laser correction and in other complicated cases, keratotomy- Surgical intervention, which involves the application of microscopic incisions on the cornea, contributing to the weakening of the strong meridian around the periphery.
With hypermetropic astigmatism, laser correction (thermokeratocoagulation)- cauterization of the periphery of the cornea, due to which its bulge and refractive force increase.
Thermokeratoplasty with laser.
The most actual way to correct astigmatism today is the excimer laser correction using LASIK technology, which is shown with astigmatism up to 3-4 Dpt.This laser correction procedure is performed on an outpatient basis with local drip anesthesia. Its essence is that ophthalmologists use a microkeratome to separate the surface layer of the cornea, then the laser in a clear the planned areas evaporate part of the corneal shell to a certain depth; then the peeled shred is returned in place.Plus, the LASIK technique also means that this intervention does not require suturing, since the finest epithelium on the edge of the shred is restored on its own.In this case, the improvement in vision is noted after only 1-2 hours after the procedure, and the full restoration of the corrected visual functions occurs within a week.
In the postoperative period, the patient is recommended:
Limitation of any loads;
Eye protection from injuries;
Exclusion of thermal procedures (saunas, hot baths);
Burying drops in the eye (as a rule, with Dexamethasone, an antimicrobial and moisturizing component);
Regular examinations of the ophthalmologist;
Passage of treatment with special devices (laser stimulation, video-computer training);
Taking vitamins for the eyes;
Execution of eye gymnastics courses;
Massage of neck and collar zone;
Hydroprocedures.Vitamins for improving vision
If it is not possible to perform laser correction of astigmatism, implantation of phakic lenses is performed.
Medicines
A patient with astigmatism should initially understand that no medications will help to get rid of astigmatism.The key objective of drug therapy is to improve circulation and metabolism in the eye tissues, especially in the cornea and the lens, which helps to slow the progression of the disease.
Eye drops with astigmatism are applied only on the prescription of the doctor in the form of treatment courses, repeated every 5-6 months.
With the lens variety of astigmatism, such drops and tablets are shown as:
Ujala;
Taufon;
Emoxipine;
Quinax;
Okyuwait;
Vitrum.Typhone is used to treat astigmatism
Prevention
To avoid acquired astigmatism, ophthalmologists recommend the following preventive measures:
Observing the lighting mode.For enhanced visual work, you need an excellent top light or a desktop source with a power of 60 - 100 W, located on the left.Important: Do not use fluorescent lamps.
Alternation of loads on the eyes with active rest.
Gymnastics for the eyes.Exercise should be done every 20-30 minutes of eye strain.
Video
conclusions
So,Astigmatism is a disease that can not be cured forever, but this violation must necessarily be corrected.Otherwise, a negative consequence may be amblyopia or strabismus. It is especially important to monitor the health of the eyes of school-age children to begin treatment of astigmatism in the early stages.
