Astigmatism - Causes, symptoms and treatment. MF.
Astigmatism is a condition in which in one eye different types of refraction or different degrees of refraction of one species are combined.
Refraction with astigmatism
There is such a thing as the main meridians - these are two perpendicular planes of the eye. Depending on their refraction, astigmatism is distinguished:
- straight - more refracts the vertical meridian,
- reverse - more refracts the horizontal meridian,
- with oblique axes
Astigmatism can be correct and incorrect( usually corneal, due to traumatic, dystrophic lesionsand inflammatory processes).At the first sight in the same meridian the same refractive force.
Correct astigmatism:
- simple - with it in one of the meridians, emmetropia( normal refraction)
- complex - in both meridians the same refraction( myopia or hypermetropia)
- mixed - in meridians different types of refraction
Normal correct astigmatism up to0.75 diopters is considered physiological, does not affect visual acuity and does not require correction.
Symptoms of astigmatism
Symptoms that can be suspected of the presence of the disease: the patient confuses similar letters, rearranges them in places, sees distorted objects, reduces visual acuity. Expressed asthenopia symptoms( rapid visual fatigue, a feeling of raspiraniya, "sand" in the eyes), there is an intolerance of glasses and their frequent replacement. Almost always, astigmatism is combined with abnormalities of refraction, myopia or hypermetropia.
So sees a person with astigmatism:
Usually, the first signs of astigmatism appear at school age, but often in adults. A thorough examination is necessary to rule out such a serious disease as keratoconus.
Keratoconus
Diagnosis of astigmatism
Methods of diagnosis:
- Visometry( determination of visual acuity) with correction and without. Wear a trial rim. In front of one eye is an opaque screen, before the other is placed lenses of different strength( with astigmatism cylindrical, which refract only in one meridian) and achieve maximum visual acuity,
- skiascopy( shadow test) - determine refraction by moving the shadow in the pupil areamovements with an indirect ophthalmoscope when viewed with transmitted light,
- mydriasis refractometry yields the most accurate results,
- biomicroscopy to identify possible causes of astigmatism( inflammatory or degenerative diseases of the cornea),
- ophthalmometry and ultrasound of the eye to determine an anteroposterior segment, becauseastigmatism in the overwhelming majority of cases is combined with myopia and hypermetropia,
- ophthalmoscopy for the detection of pathology of the vitreous and fundus,
- computer keratotopography for determining the degree of corneal astigmatism. During the study, the thickness and refractive force are measured at more than 8,000 points. Identify the slightest violation of refraction.
Astigmatism treatment
Astigmatism must be corrected and treated in a timely manner to prevent the development of complications. Correction: eyeglass, contact, laser and microsurgical .Indications: decreased visual acuity, asthenopia symptoms and progression of myopia or farsightedness.
The first species( glasses ) is not tolerated by many patients, but most of them prefer wearing glasses. Lenses are made special, with a cylindrical component. Points are selected strictly individually. They can not be bought simply in optics or in the market. The power of a cylindrical lens should coincide with the degree of astigmatism, and the spherical ones are selected according to the rules for correction of myopia or hypermetropia. These glasses are prescribed for permanent wearing.
Contact correction of is performed using toric lenses. Its advantage is that a single optical system with an eye is formed, in contrast to glasses that are at a certain distance. To use toric lenses you need special skills, which the ophthalmologist teaches. Night( orthokeratological) lenses also found application with a small degree of astigmatism.
If there is a difference in the optical strength or thickness of the cornea, then after keratotopography, is possible with the astigmotomy , in which microscopic incisions that weaken the strong meridian are applied on the periphery. Indications: astigmatism more than 6 dptr, children under 18 years, thin cornea( laser correction is not possible), as well as various refraction in the meridians.
Restoration and moisturization of eye tissues with astigmatism.
With astigmatism, as with many ophthalmic diseases, the eyes need to be hydrated and restored by creating a protective film on the surface of the cornea. With such a task cures funds based on hyaluronic acid, for example, eye drops "Artelak Splash", which are shown for the elimination of mild symptoms of eye fatigue, occurring up to 2-3 times a day. With intensive manifestation of dryness, which worries a person throughout the day, one should pay attention to drops of "Artelak Balance", which includes a protector providing a long-lasting moisturizing effect, and vitamin B12, which has pronounced antioxidant properties.
Indications for excimer laser surgery is astigmatism up to 4 dpt. This is an outpatient, almost painless procedure, after which the patient immediately notices a significant improvement in visual acuity. The essence of it is that after the formation of the valve, the cornea is ground in clearly marked places at a certain depth. After surgery, it is necessary to limit physical and visual loads, protect eyes from injuries( wearing glasses, for example), hot tubs, sauna, alcohol for a month. Recommended instillation of drops of dexamethasone( Offtan-dexamethasone, Maxidex) first 3 times a day, reducing to 1 time, 3 weeks;antibacterial( Tobrex, Floxal, Oftakwix) 3 times a day for a week, as well as moisturizing drops situationally( Oftagel, Oxial, Systein).Regular examinations by an ophthalmologist are mandatory.
1-2 times a year, courses of vitamin preparations ( Vitrum, Okuvaite-lutein, Cernica-forte, etc.) and hardware treatment ( laser stimulation, computer programs) must be taken 1-2 times a year.
Complications of astigmatism
Untimely and inadequate treatment can lead to complications such as reduced visual acuity before the development of amblyopia( "lazy" eye, in which vision does not improve with correction), strabismus.
Prevention of astigmatism
The most important thing for health is the prevention of diseases. With regard to astigmatism, it is necessary to dose visual loads, or alternately alternate them with physical exercises and gymnastics for the eyes. It is strictly forbidden to read lying or in poor light. You can use special perforation glasses.
Doctor ophthalmologist Letyuk T.Z.