Astigmatism: symptoms, photos, causes and treatment
The eye is in fact an optical system, which consists of several refractive media. The image of objects, refracted in these environments, normally focuses on the retina.
Astigmatism is a vision pathology in which the optical system does not have a single focus, so a clear image on the retina is not focused.
To better understand what astigmatism is, you need to become familiar with the concept of clinical refraction. This term denotes the position of the focus of the eye relative to the retina.
If the focus is on the retina, then the refraction is emmetropic( normal).If the image is focused behind the retina - refractive hypermetropia( farsightedness), and if the retina is myopic. See( causes of myopia).
With astigmatism in one eye there are simultaneously different types of refraction or one kind with different refractive power.
How does astigmatism develop in the eyes, and what is it? The main cause of astigmatism is the incorrect configuration of the optical system of the organ of vision. It is observed with uneven curvature of the cornea or irregular lens shape.
The causes of acquired astigmatism can be:
With congenital astigmatism, symptoms are not very specific. They begin to appear already at preschool age. The child complains of poor eyesight, confuses letters, and changes them in places.
May disturb headaches, rapid visual fatigue. Sometimes there is a feeling of "sand" in the eyes. It can be difficult for patients to pick up glasses, they often have to be replaced.
Adult patients complain of blurred vision. Objects seem to the person uneven, indistinct and deformed. Burning and pain in the eyes, their redness are often disturbed. With increased visual load, double vision appears, the definition of distance to objects is violated.
Often to improve the clarity of vision, patients tilt their head sideways, screw up their eyes or pull down the lower eyelid. In adults, one of the symptoms of astigmatism can be chronic blepharoconjunctivitis, which is difficult to treat.
Through the eye, it is possible to arbitrarily draw a number of meridians( planes) that pass through the rear and front poles and lie on the main optical axis.
With the right one of the meridians refracts the most weakly, and perpendicular to it - most strongly. Incorrect astigmatism occurs in the following cases:
Simple astigmatism can be myopic( in one of the meridians the refraction is normal, in the other - myopic) and hypermetropic( refraction of one meridian - normal, the other - hypermetropic).
With complex astigmatism in both major perpendicular planes there are different degrees of one refraction. Mixed astigmatism is characterized by hypermetropic refraction in one meridian and myopic refraction in the other.
Depending on the causes and time of occurrence, the acquired and congenital astigmatism is distinguished. It can also be physiological( if the difference in the refraction of meridians is not more than 1 diopter and does not affect visual acuity) and pathological( the difference is more than 1 diopter, vision is impaired).
Various instrumental methods are used to diagnose astigmatism.
Treatment and subsequent correction of astigmatism can be carried out with the help of contact lenses, glasses and microsurgical methods.
Astigmatism is a vision pathology in which the optical system does not have a single focus, so a clear image on the retina is not focused.
To better understand what astigmatism is, you need to become familiar with the concept of clinical refraction. This term denotes the position of the focus of the eye relative to the retina.
If the focus is on the retina, then the refraction is emmetropic( normal).If the image is focused behind the retina - refractive hypermetropia( farsightedness), and if the retina is myopic. See( causes of myopia).
With astigmatism in one eye there are simultaneously different types of refraction or one kind with different refractive power.
Causes of
How does astigmatism develop in the eyes, and what is it? The main cause of astigmatism is the incorrect configuration of the optical system of the organ of vision. It is observed with uneven curvature of the cornea or irregular lens shape.
Most often this pathology is hereditary. Astigmatism can occur due to congenital uneven pressure of the eyelids, osseous bones and oculomotor muscles.
The causes of acquired astigmatism can be:
- various injuries, which result in scarring of the cornea or subluxation of the lens;
- ophthalmic operations;
- trauma and anomalies in the structure of the dentoalveolar system( open bite, prognathia, congenital absence of many teeth);
- dystrophic processes in the cornea( keratoconus, keratoglobus);
- corneal opacity as a result of the inflammatory process( herpetic keratitis, blennorea, etc.).
Symptoms of astigmatism
With congenital astigmatism, symptoms are not very specific. They begin to appear already at preschool age. The child complains of poor eyesight, confuses letters, and changes them in places.
May disturb headaches, rapid visual fatigue. Sometimes there is a feeling of "sand" in the eyes. It can be difficult for patients to pick up glasses, they often have to be replaced.
Adult patients complain of blurred vision. Objects seem to the person uneven, indistinct and deformed. Burning and pain in the eyes, their redness are often disturbed. With increased visual load, double vision appears, the definition of distance to objects is violated.
Often to improve the clarity of vision, patients tilt their head sideways, screw up their eyes or pull down the lower eyelid. In adults, one of the symptoms of astigmatism can be chronic blepharoconjunctivitis, which is difficult to treat.
Classification
Through the eye, it is possible to arbitrarily draw a number of meridians( planes) that pass through the rear and front poles and lie on the main optical axis.
Perpendicular meridians, which have the greatest refraction difference, are called the main ones. Depending on this, the correct and incorrect types of astigmatism are distinguished.
With the right one of the meridians refracts the most weakly, and perpendicular to it - most strongly. Incorrect astigmatism occurs in the following cases:
- refraction in the transition from one main meridian to another changes in jumps rather than gradually;
- the main meridians in relation to each other are not perpendicular;
- during one meridian the refraction is different.
- reverse;
- straight;
- with oblique axes;
- simple( myopic and hypermetropic);
- complex( myopic and hypermetropic);
- mixed;
Simple astigmatism can be myopic( in one of the meridians the refraction is normal, in the other - myopic) and hypermetropic( refraction of one meridian - normal, the other - hypermetropic).
With complex astigmatism in both major perpendicular planes there are different degrees of one refraction. Mixed astigmatism is characterized by hypermetropic refraction in one meridian and myopic refraction in the other.
Depending on the causes and time of occurrence, the acquired and congenital astigmatism is distinguished. It can also be physiological( if the difference in the refraction of meridians is not more than 1 diopter and does not affect visual acuity) and pathological( the difference is more than 1 diopter, vision is impaired).
Diagnosis of astigmatism
Various instrumental methods are used to diagnose astigmatism.
- 1) Visometry is the easiest way. The patient wears a special frame. One eye is closed by an opaque flap, and before the other, lenses with different refractive power are successively placed. Thus, the refraction in both meridians is determined.
- 2) Skiascopy - the definition of refraction by moving the shadow in the pupil using the rocking movements. An indirect ophthalmoscope is used.
- 3) Refractometry is the measurement of refraction in the meridians in the state of mydriasis( drops dilating the pupil are instilled in the eye).
- 4) Biomicroscopy - with the help of a biomicroscope identify possible causes of the disease( inflammatory and degenerative processes in the cornea or lens).
- 5) Ophthalmometry in combination with ultrasound of the eye to measure the size of the eyeball( lengthening or shortening the axis of the eye can be one of the factors causing astigmatism).
- 6) Ophthalmoscopy( examining the fundus and vitreous body).
- 7) Computer keratotopography - the most accurate method of diagnosing astigmatism with the definition of its type and degree( the refractive force is measured at 8000 points).
Astigmatism treatment
Treatment and subsequent correction of astigmatism can be carried out with the help of contact lenses, glasses and microsurgical methods.
- 1) Contact correction - permanent contact lenses - the preferred type of correction for this disease. They are manufactured individually to compensate for the corneal irregularities.
- 2) Ophthalmic correction - with simple astigmatism use spherical lenses, since one meridian has a normal refraction. With complex and mixed astigmatism, a combination of spherical and cylindrical lenses is required. Correction points are selected strictly individually according to the types and degrees of refraction in the main meridians.
- 3) Surgical interventions - surgical treatment of astigmatism includes astigmotomy and excimer laser operations. With astigmotomy, microscopic incisions are applied to the cornea, which weaken the strong meridian. Laser treatment consists in grinding the cornea to a certain depth. This operation is often performed on an outpatient basis. Patients almost immediately feel an improvement in visual acuity.