What is astigmatism?
Astigmatism is a refractive error in a certain axis, in which the image on the retina appears out of focus. Astigmatism is among the most frequent vision problems and it can be associated with other refractive errors or eye diseases, as we will see later.
To better understand what is astigmatism in the eyes or ocular astigmatism, look at the images or photos above. With normal vision, the image is focused on the retina and on a single point of focus. The retina plays an important role in vision, as it receives images and transmits them to the brain through the optic nerve.
In the eye with astigmatism, objects are focused on more than one point, thus distorting the vision, that is, the images are distorted when passing through the cornea and, as such, appear out of focus when projected onto the retina. Consequently, in vision with astigmatism, the images transmitted to the brain are blurred or distorted, causing blurred or “blurred” vision.
Symptoms of astigmatism
People with ocular astigmatism have the following symptoms: blurred near and far vision, that is, objects that are closer or farther away are distorted. The astigmatist or person with astigmatism may experience eye fatigue (tired eyes) or headaches (headache), which are the most frequent symptoms of astigmatism.
At an early stage, astigmatism may be asymptomatic (without symptoms), however, as the disease worsens, the first signs and symptoms appear.
Causes of Astigmatism
The causes of ocular astigmatism are unknown, and refractive error is usually present from birth. Usually, the defect is in the curvature of the cornea whose shape is more oval than round. The curvature of the cornea is asymmetrical, thus blurring the vision.
Astigmatism can also be induced by certain eye diseases, such as keratoconus, and pterygium, among others.
We say that we are facing irregular astigmatism when the curvature of the cornea is very uneven. In turn, we call it regular astigmatism when there is only a difference in curvature between two perpendicular meridians of the cornea.
We are dealing with simple astigmatism when astigmatism is the only existing refractive error or with compound astigmatism when this is associated with another refractive error, such as myopia or hyperopia. That is, two combinations can occur:
- astigmatism and myopia ;
- astigmatism and hyperopia.
Myopic astigmatism
We say that we are facing compound myopic astigmatism when the two refractive errors exist simultaneously (astigmatism and myopia together). Astigmatism with myopia is a very common eye problem.
This visual anomaly (myopia and astigmatism together) is common in children and can have negative repercussions on school success, as it causes hypovision. If astigmatism is unilateral, early correction in children is urgent (before the age of six), as it can cause amblyopia or loss of physiological vision that may be irreversible.
Hyperopic astigmatism
Compound hypermetropic astigmatism (astigmatism and hypermetropia together) is a frequent visual problem in both sexes.
When present in children, it can lead to major irreversible vision losses (amblyopia) if not corrected in a timely manner before 6 years of age.
Childhood astigmatism
The term infantile or childhood astigmatism is used whenever refractive error affects children. The first visit to the ophthalmologist should take place in the first year of life to screen for possible refractive errors, namely anisometropias, thus avoiding possible permanent visual impairments (amblyopias).
Most children do not know how to refer when they do not see well. He believes that the vision he has is normal because he has never seen better. The early detection and treatment of vision problems in children is essential not only to avoid possible amblyopias but also to prevent problems in their development.
It is estimated that between 10 and 15% of school-age children have eye problems that can influence their performance at school.
To learn more about astigmatism in children, see more information on myopic and hyperopic astigmatism.
Is astigmatism curable?
Astigmatism has no cure. However, if appropriate measures are taken to correct the refractive error, we will be able to restore good visual acuity to patients, compatible with the needs of their daily tasks. See below how to treat or correct astigmatism.
Treatment/correction of astigmatism
The treatment for astigmatism involves correcting the refractive error. Any astigmatism can be corrected through glasses or contact lenses. Surgical correction is also possible, resorting to laser (LASIK) or operating with intraocular lenses.
The ophthalmologist is responsible for indicating the most appropriate method of astigmatism correction for a given patient, based on several factors, such as age, ability to adapt to glasses or contact lenses, astigmatism values, etc.
See below for more information on how to correct astigmatism, namely types of lenses and surgery.
Glasses for astigmatism
Ocular astigmatism can be compensated with a toric lens (cylindrical lens) that will compensate for the corneal deficiency. The lens does not have the same thickness over the entire surface and the difference is greater the higher ocular astigmatism, in order to compensate for it.
Astigmatism is corrected with glasses, approximately until the age of fifteen, since from this age on it can be compensated by contact lenses for astigmatism. As we will see below, there is also the possibility of performing surgical treatment to correct astigmatism.
Astigmatism surgery
From the age of twenty, if the refractive error is stabilized, we can perform astigmatism surgery. The purpose of the operation or surgery is to correct astigmatism, thus restoring normal vision to patients without the need for glasses or contact lenses. Surgery for astigmatism can be performed with a laser (LASIK surgery) up to 6 diopters or through an intraocular lens in the anterior or posterior chamber (if you have no indication for LASIK). Operating astigmatism is currently a very safe option although, like any surgery, there are some risks and complications that must be considered.
Astigmatism can also be treated with intraocular lenses, placed in the capsular bag in patients over 45-50 years old, as well as presbyopia and other refractive errors.
In patients who suffer from astigmatism and myopia together, surgery for astigmatism and myopia makes it possible to correct both refractive errors simultaneously. Also, the most frequently used techniques are LASIK and intraocular lenses.
Surgical results are excellent if we take into account complementary diagnostic tests, indications and contraindications for surgical techniques, based on age, values and stabilization of astigmatism.
