Mixed astigmatism

El astigmatism It is a refractive defect that occurs when the curvature of the cornea is not uniform in all its parts, preventing the correct focus of objects at any distance.

This vision disorder can occur in isolation or be accompanied by other defects such as myopia and / or the farsightedness

El mixed astigmatism is a type of astigmatism which originates when one main eye meridian focuses as myopic and the other as hyperopic. Generally, it is usually caused by a genetic cause, although it can also derive from eye surgery, trauma or disease. 

Mixed astigmatism

El astigmatism It is a refractive defect that occurs when the curvature of the cornea is not uniform in all its parts, preventing the correct focus of objects at any distance.

This vision disorder can occur in isolation or be accompanied by other defects such as myopia and / or the farsightedness

El mixed astigmatism is a type of astigmatism which originates when one main eye meridian focuses as myopic and the other as hyperopic. Generally, it is usually caused by a genetic cause, although it can also derive from eye surgery, trauma or disease. 

What is mixed astigmatism?

El astigmatism is a refractive defect what happens when the cornea has an abnormal curvature in all its structure, causing light to be projected at various points on the retina. Furthermore, it is usually congenital and it is believed that all human beings are born with a certain degree of astigmatism. 

El Mixed astigmatism occurs when one meridian of the eye focuses behind the retina and the other focuses in front of the retina. This means that there is a combination of astigmatism with one myopic axis and the other hyperopic axis.

Mixed astigmatism

Types of astigmatism

El astigmatism can be simple or compound. When is simple a single axis does not focus on the retina while the other one does. When the astigmatism is compound means that both axes (vertical and horizontal) don't focus on the retina.

Myopic

El myopic astigmatism work when one or both meridians eye focus as myopic, in other words, ahead of the retina. If both meridians are myopic, they are so to a different degree.

There are two types of myopic astigmatism: simple and compound. The simple myopic astigmatism occurs when one axis focuses on the retina and the other does not. He compound myopic astigmatism occurs when both axes do not focus on the retina.

hypermetropic

El hyperopic astigmatism occurs when one or both meridians of the eyes are farsighted, that is focus behind the retina. If both meridians are farsighted, they are too to a different degree.

We say that we are facing a simple hyperopic astigmatism when there is a meridian that does not focus on the retina, while we talk about compound hyperopic astigmatism when the two axes do not focus on the retina.

Mixed

El mixed astigmatism originates when an eye meridian focuses like myopic, ahead of the retina, and the other focuses as hyperopic, behind the retina. 

Causes of mixed astigmatism

Why does mixed astigmatism occur? This problem manifests itself when the cornea does not have the same curvature throughout its structure, causing light, instead of projecting onto the retina, projected at several points at the same time.

La corneal irregularity can cause one axis focuses behind the retina and one in front of the retina, causing mixed astigmatism, that is, myopic and hypermetropic astigmatism at the same time.

Generally, Astigmatism is almost always congenital and genetic, although it can also be caused by trauma, surgical complications or eye diseases such as keratoconus

Symptom

Astigmatism is characterized by causing blurred vision or distortion of objects and images at any distance. However, when this defect is accompanied by myopia and hyperopia, the symptoms are more pronounced. 

Those who suffer from mixed astigmatism can perceive sharp images on one meridian and blurred on the other, see oval-shaped circles and lights with tails, light halos or flashes. The most prominent symptoms are:

  • Headache.
  • Fatigue.
  • Eye irritation.
  • Blurry vision.
  • Image distortion.

It should be noted that people with astigmatism usually tilt their heads to the side to see better or squint to suppress the rays of light that come from the most affected meridian.

Can mixed astigmatism be operated?

El mixed astigmatism can be corrected using glasses with toric lenses, since they are convergent on one axis and divergent on the other.

However, when the eyeball finishes its development process at approximately 21 years of age, at that time it is possible to contemplate the option of correct mixed astigmatism permanently through the refractive surgery.

There are different techniques to carry out this procedure. The most commonly used techniques today for astigmatism operation are:

operate mixed astigmatism

FemtoLasik

laser eye surgery FemtoLasik to correct mixed astigmatism is done entirely with laser technology and It is the most modern and secure that currently exists..

First femtosecond laser is applied, since it is more precise and exact than traditional techniques, for separate corneal tissue. The great advantage of femtosecond laser is that we do this step without making any cuts.

Once this maneuver is done, we apply the second laser, the excimer laser programmed according to the needs of the patient to eliminate mixed astigmatism. Importantly, the femtosecond laser reduces the risk of complications, is safer, and offers a faster recovery. 

PRK

La PRK surgery to correct mixed astigmatism consists separate the corneal epithelium to shape the curvature of the cornea using an excimer laser.

After surgery, the epithelium regenerates on its own. The patient should wear therapeutic contact lenses for as long as the surgeon deems necessary while the corneal epithelium is regenerating.

LASIK

The technique of lasik surgery It is the most used technique today.

The procedure is carried out by performing a corneal flap using a blade (microkeratome). Once the corneal flap is done, we apply the excimer laser on the tissue to eliminate mixed astigmatism.

Once this process has been carried out, the corneal lamella is placed in its place again without the need for any type of suture.

intraocular lens

Another alternative for correct mixed astigmatism is implantation of an intraocular lens, a highly recommended option for patients who are not candidates for laser surgeries such as FemtoLASIK, Lasik, or PRK.

The toric intraocular lenses are designed for treat astigmatism permanently, since they allow correcting the asymmetry of the eye and significantly improve distance and near vision.

These lenses are manufactured with a custom curvature, according to the characteristics of the patient's eye, and provide great visual sharpness. The placement of these intraocular lenses for mixed astigmatism surgery It must be carried out very precisely for its correct implantation.

When the mixed astigmatism affects children, must be correct using glasses or contact lenses until the eye is fully developed and you can opt for refractive surgery. It is necessary to wait until the eyeball is fully developed to operate mixed astigmatism, because, otherwise, there is a risk of suffering astigmatism again.

At present, gas permeable contact lenses They are also an option for those patients who wish to correct mixed astigmatism and are not candidates for refractive surgery. It is a kind of rigid lens that acts by molding the cornea as a refractive structure so that the axes are focused on the retina.

Nowadays, Refractive surgery is the most effective and safest option to correct refractive defects such as myopia, hyperopia and / or the different types of astigmatism permanently..

However, before operating mixed astigmatism, it is important to carry out a complete review of the ocular structure to determine if the patient is a candidate or not and which technique is the most suitable according to his needs. 

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What is mixed astigmatism and how to treat it?
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What is mixed astigmatism and how to treat it?
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Learn about mixed astigmatism, what are its causes, its symptoms, and how to treat it.
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Área Oftalmológica Avanzada
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