Astigmatism is a pathological change in vision in which the light beam is incorrectly focused on the retina of the eye. In normal condition, the cornea and lens have a spherical rounded shape. A ray of light passing through them gathers on the retina at one point. With astigmatism, the sphericity is broken, has different curvature. The cornea and lens are elongated in the form of an ellipse. Accordingly, there is a different optical refractive power, the light is incorrectly refracted. Several focal points are formed on the retina, which gives a distorted image.
Types of diseases
The most common is corneal astigmatism, the lens is less common. More often, the disease is diagnosed in one eye, but it can also be bilateral.
It occurs due to genetic disorders (asymmetric development of the bones of the eye socket, disorders in the work of the muscles of the eye). This type of astigmatism is often found in infants with pigmented rhinitis, albinos or with poisoning by toxins during intrauterine development, if the expectant mother used alcohol or drugs during pregnancy.
It develops due to injuries and inflammation of the eye, corneal dystrophy, scarring on it.
Simple (hypermetropic or myopic).
Farsightedness or myopia is observed on one meridian of the eyeball, there are no refractive changes on the other.
A combination of myopia and hypermetropia is observed in the main meridians of the eye.
Farsightedness is present on one eye meridian, myopia on the other.
Astigmatism up to 3 diopters is considered mild, 3-6 – medium, more than 6 – high.
Signs that should alert
The symptoms of the disease do not appear immediately. With a mild degree of astigmatism, a person can see the letters from the bottom line even when checking the vision on the tables. Gradually, he begins to notice various signs peculiar to astigmatism.
The main symptoms of the disease include blurred images, rapid eye fatigue, discomfort. It becomes difficult to read letters that are similar to each other, but differ in the presence of an extra element (for example, in the letters B and P, C and O). But if there are no letters similar in shape in a word, a person distinguishes them without problems. Symptoms, in addition to defocusing and distorting the visual image, are supplemented by burning and soreness in the eyes, double objects, a feeling of a speck in the eye, problems with visually determining the distance from one object to another.
With a weak degree of astigmatism, a person may not notice any symptoms. First, the refractive ability of the eye is compensated by the work of the ciliary muscle, which changes the shape of the lens and focuses vision near. Over time, the symptoms increase, problems with focusing vision worsen at dusk and in the dark, when the pupil dilates. At an average degree, the outlines of objects begin to blur, you have to strain your eyes a lot to examine the object or read the text. A high degree is combined with migraine-like headaches, “floating” contours of objects.
One can easily imagine how a person with moderate and high astigmatism sees. To do this, you need to look at your reflection in an ordinary tablespoon. The picture is distorted, some features are blurred, others are disproportionate. And this does not change when the spoon is close or far away.
A number of studies are conducted to identify astigmatism and determine its degree.
- corneal curvature measurement (keratometry);
- inspection with a slit lamp;
- shadow test (skiascopy);
- checking visual acuity using a table (without correction and with it);
- determination of the refractive power of the cornea (refractometry).
Based on these studies, it can be concluded about the development of corneal astigmatism. Usually, the disease does not develop on its own. It is accompanied by strabismus, nearsightedness or farsightedness.
It is especially important to identify problems with focusing in children in time. Their astigmatism is most often congenital and develops at the age of 1-3 years, has a stable character. Over time, the “lazy eye” syndrome appears. Due to the fact that an incorrect picture is formed on the retina from an early age, that is, inadequate stimulation of the visual system occurs, changes are observed in the structural eye departments due to unequal refraction of light streams and a decrease in visual acuity develops that cannot be corrected. The child cannot learn to read for a long time, there are difficulties with writing.
Conservative and innovative methods are used for treatment. First, they try to correct their vision with the help of special glasses with spherical or cylindrical lenses. This is not a treatment, it just improves the quality of life of patients. But the glasses have one significant drawback. A person sees well in them if he looks straight. If he tries to look to the right or to the left without turning his head, the image is distorted again. This causes dizziness, fatigue and eye discomfort. Another option is to wear soft toric lenses. They are adjacent to the cornea and correct vision in all directions without distortion.
Adults are often prescribed vision correction with a laser, which excises part of the cornea. If the cause of astigmatism lies in the deformation of the lens, it is removed and replaced with an intraocular lens. In some cases, cauterization of the cornea with a laser or needle (thermokeratocoagulation) is practiced. With this operation, the thickness of the corneal layer is reduced to increase the refractive power.
In children with astigmatism, correction with glasses is mainly used. Orthokeratology is shown – wearing hard contact lenses at night. The ocular structures are still growing, so surgical intervention is not carried out.
As preventive measures for astigmatism, an optometrist should be visited twice a year to check vision and examine eye structures. Perform gymnastics for the eyes, which helps to relax the eye muscles, improve blood flow and normalize metabolic processes.
When working with a computer or other gadgets, take breaks every 30 minutes. Children should limit the time spent on gadgets, monitor the correct illumination of the workplace when performing lessons and posture. For adults and children, it is useful to drink courses of vitamins for the eyes.