Astigmatism is simply a condition that occurs when the cornea (the outer, transparent part of the eye that transmits light and protects the iris and lens) does not have the same symmetry in all its parts.
The cornea of the eye without astigmatism is round in all its parts (similar to a basketball), but some parts of the cornea of this defective eye appear to be more or less round than others (similar to a rugby ball). This causes blurred and distorted vision, both near and far, due to emmetropic (non-prescription) eyes where the image is centered on a single line on the retina. In contrast, in the astigmatic eye, the image is not centered on the retina because the surface of the cornea is not completely smooth and regular. For the image to be seen clearly, the horizontal and vertical light rays reaching the eye’s optical system must create a focal point on the retina. Astigmatism is a subtle error in which vertical and horizontal light rays have different focus on the retina. It may be associated with nearsightedness and farsightedness.
HOW DOES ASTIGMATISM AFFECT VISION?
Astigmatism usually causes blurred vision both near and far, eye fatigue, headache; These symptoms do not always mean you have astigmatism. To determine the cause of your symptoms, see your optometrist for a complete eye examination.
Astigmatism can affect a child’s performance in school and cause amblyopia (lazy eye) and vision loss.
This is why an eye examination by a pediatrician, or optometrist is very important in childhood. If you notice astigmatism or other eye problems, consult an ophthalmologist for proper treatment.
CAUSES OF ASTIGMATISM
Astigmatism is caused by lack of corneal symmetry. It has hereditary factors.
Astigmatism can also develop in the following situations:
- ocular disease : it is associated with certain corneal diseases such as keratoconus.
- eye injury: when a lesion is produced that damages the cornea, the cornea is no longer uniform and regular. When the cornea is irregular, blurred vision occurs.
- after surgery
- misuse of contact lenses
TYPES OF ASTIGMATISM
- Regular astigmatism: it is the astigmatism most common. It occurs when two principal meridians form a right angle. This is usually due to changes in the cornea, which shows different degrees of curvature of the perfect meridian.
- Irregular astigmatism: develops when there is a very severe irregularity over the entire surface of the cornea. The principal meridians do not form a 90 degree angle and cannot be corrected with glasses because each point of the cornea needs a different prescription due to the high irregularity of the cornea.
SYMPTOMS OF ASTIGMATISM
- Visual acuity is reduced, both far and near, as well as the visualization of images that appear longer.
- The shape of the object is distorted.
- It causes blurred vision both far and near: Blurred vision is usually evident at night or in low light conditions.
- visual fatigue.
- itching and irritation of the eyes: due to the excess of effort that makes the eye can appear sensation of itching in the eyes especially in children who suffer from astigmatism have much tendency to fortaar the eyes in a continuous way.
Astigmatism remains stable throughout life. It is not usual that an elevated astigmatism appears suddenly, unless it is caused by a disease. Nor is it common that once diagnosed, there are sudden increases in astigmatism prescription.
In general, the most important symptom is distorted or blurred vision of near and distant objects.
If you have one or more of these symptoms, it is best to consult an ophthalmologist who will examine the patient and determine whether or not you really have astigmatism.
Astigmatism cannot be prevented, but it can be diagnosed with a thorough eye examination, especially in childhood. In childhood, uncorrected astigmatism can cause lazy eye (amblyopia). For this reason an eye examination should be performed, even if there are no symptoms.
TREATMENT OF ASTIGMATISM
Astigmatism can be diagnosed with a comprehensive eye examination. Current treatment options for astigmatism correction are:
- Correction with glasses
- correction with contact lenses. This is the simplest way to correct astigmatism.
- Laser corneal surgery
In addition, astigmatism can be corrected by correcting other refractive errors such as nearsightedness, farsightedness or presbyopia.
LASER CORNEAL SURGERY TO CORRECT ASTIGMATISM
Refractive surgery can reduce or even eliminate astigmatism. Its purpose is to get the image correctly focused on the retina. There are 2 types of surgery:
- Laser surgery for astigmatism, which works at the corneal level.
- Astigmatism surgery contact lenses implant.
Currently, eye surgery is highly dependent on technological advances. The most important factor for the success of the operation:
- Good patient selection by the surgeon.
- Procedure that the doctor can use to work
The Best candidates for astigmatism refractive surgery are:
- Adults with stable astigmatism of less than six diopters. In case of severe astigmatism, diopters can be reduced, but not completely.
- Patients with healthy eyes, without eye problems, corneal ulcers or other eye diseases.
Refractive surgery for astigmatism is not valid in these cases:
- there is an autoimmune disease in the medical history.
- Pregnant or lactating.
- You have an eye disease or injury in your medical history.
- You are being treated with a medication that may affect the healing process or vision.
- You only have vision in one eye.
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