Understanding of Astigmatism, characteristics, cause and ways of treating
Astigmatism or cylindrical eyes are visual disturbances due to abnormalities in the corneal arch or lens. This condition causes blurred vision, both near and far. Astigmatism can occur together with nearsightedness (hyperopia) or nearsightedness (myopia). Although it generally occurs at birth, astigmatism can also be caused by an injury to the eye, or because of eye surgery.
Astigmatism is divided into two types, based on the location of the disturbance. Astigmatism caused by abnormalities in the corneal curvature is called astigmatic cornea. Whereas if the abnormality in the curvature of the eye lens is called lenticular astigmatism.
Symptoms of Astigmatism
In some cases, astigmatism does not cause symptoms at all. If there are symptoms, complaints that everyone feels can vary, including:- Vision distortion, for example, sees a straight line appearing tilted.
- Unclear or unfocused views.
- Hard to see at night.
- The eyes are often tense and easily tired.
- Squint often when you see something.
- Sensitive to light beams (photophobia).
- Difficulty distinguishing similar colors.
- Double vision (in the case of severe astigmatism).
- Dizziness or a headache.
Causes and Risk Factors for Astigmatism
Astigmatism is caused by abnormalities in the curvature of the cornea or eye lens. It is not known what triggers the disorder but is thought to be related to heredity.
The cornea and lens are parts of the eye that function to refract and pass on the light entering the retina. In eyes that experience astigmatism, the incoming light is not completely refracted, so the resulting image becomes out of focus.
Although it generally occurs at birth, astigmatism can also occur due to an eye injury, or because of side effects from eye surgery. Some other factors that can increase the risk of astigmatism are:
- Nearsightedness or farsightedness.
- Have other eye disorders, such as keratoconus (corneal degeneration) or corneal thinning.
- Suffering from Down syndrome.
- There is a lump on the eyelid that presses the cornea.
- Premature birth, or with low birth weight.
Diagnosis of Astigmatism
To ensure a diagnosis of astigmatism, the ophthalmologist must conduct a thorough eye examination, including:
Vision sharpness test. In this test, the doctor will ask the patient to read a series of letters of various sizes, from a distance of 6 meters.
Refraction test. The doctor will start this test by measuring the intensity of the light received by the retina. Measurements can be made using a machine, or patients will be asked to read the smallest letters through a device called a phoropter. If the patient cannot see the letter clearly, the size of the lens will be corrected, until the letter can be read perfectly.
Keratometry. Keratometry is a procedure to measure the corneal curvature using a keratometer. In addition to determining the size of the right contact lens, this procedure can also be used to check corneal conditions after eye surgery.
Topography This test aims to map the corneal arch and diagnose the possibility of keratoconus. The results of this test will help the doctor determine the type of eye surgery to be performed.
Astigmatism is measured by a dioptric scale. Healthy eyes without astigmatism, assessed by diopters 0. But in most people, diopters range between 0.5-0.75.
Treatment of Astigmatism
Treatment of astigmatism or cylindrical eyes depends on the dioptric scale of the patient. In the cylindrical eye above 1.5, generally, the doctor will advise the patient to use glasses or contact lenses. If the patient wants another treatment method, refractive surgery can be an option. Some surgical methods that can be done to treat astigmatism are:
Laser-assisted keratomileusis there. uses a laser to reshape the cornea, by removing part of the corneal tissue. The goal is to increase the focus of light on the retina.
Laser-assisted subepithelial keratectomy (LASEK). In this procedure, the surgeon relaxes the corneal protective layer (epithelium) with special alcohol, then reshapes the cornea using a laser. After that, the epithelium will return to its original position.
Photorefractive keratectomy (PRK). The CRP procedure is the same as LASEK, only with CRP, the epithelium will be removed. The epithelium will naturally form again following the new corneal curvature.
In addition to the three methods above, there are other refractive surgical methods, namely refractive lens exchange (RLE), or also called clear lens extraction (CLE). RLE uses artificial lenses to replace eye lenses that cannot be repaired. In addition to treating astigmatism, RLE can also be applied to cataract patients.
Complications of Astigmatism
Astigmatism that occurs only in one eye from birth can trigger amblyopia (lazy eyes), or what is commonly called lazy eyes. This condition occurs because the brain is used to ignore
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