What is Astigmatism?
Astigmatism or cylindrical eyes are visual disturbances caused by defects in the curvature of the lens or cornea. This condition can cause vision to become distorted or blurred.
Astigmatism is usually present at birth, but can also be caused by injury to the eye later in life or as a complication of eye surgery.
Visual acuity at various distances will be reduced. This can be experienced by people with nearsightedness or also called myopia and farsightedness or called hypermetropia.
If not treated properly, astigmatism can cause headaches and tired eyes, especially if you use your eyes for a long time.
Symptoms of Astigmatism
Astigmatism can interfere with the sufferer’s daily activities. Some of the symptoms of astigmatism are:
- Blurred or unfocused vision.
- Dizzy.
- Tired eyes.
- Sensitive to bright light (photophobia).
- Difficulty distinguishing colors that are next to each other.
- Difficulty seeing images as a whole, for example, straight lines appearing slanted.
- In severe astigmatism, sufferers may experience double vision.
Causes of Astigmatism
Cylindrical eyes are caused by an imperfect lens or cornea, resulting in light entering the eye being out of focus when transmitted to the retina.
Therefore, the vision produced by the eye becomes blurry.
Based on the cause, astigmatism is divided into two types:
- Astigmatism caused by defects in the cornea of the eye is called corneal astigmatism.
- Astigmatism caused by defects in the lens of the eye is called lenticular astigmatism.
Meanwhile, based on the type of damage, astigmatism is also divided into two, namely:
- Regular astigmatism is when one side of the cornea is curved more than the other. This is a common condition and can be treated with glasses or contact lenses.
- Irregular astigmatism is when the cornea is uneven not only on one side but across the entire surface of the cornea. This condition occurs due to an injury that leaves a scar on the cornea. This condition can be treated with the help of contact lenses and not with glasses.
Risk Factors for Astigmatism
There are several factors that can increase the risk of developing astigmatism:
- Complications from eye surgery.
- Injury to the cornea due to infection.
- Conditions of the eyelid that interfere with the structure of the cornea. Such as a lump on the eyelid that presses on the cornea.
- Keratoconus and keratoglobus, which are conditions where the cornea can change shape, either bulging or thinning.
- Other eye conditions affecting the cornea or lens.
- Myopia, such as hypermetropia and hyperopia or farsightedness (myopia) can accompany astigmatism.
Astigmatism Diagnosis
To find out whether a patient has astigmatism, the doctor needs to perform the following eye tests:
1. Vision Test
The most common type of vision test is a visual acuity test. It involves asking a person to read a series of letters of varying sizes from a distance of 20 feet.
2. Refraction Test
Refraction or phoropter testing is a test using an optical refractor machine that has several corrective glass lenses with different strengths.
Later, the doctor will ask the person with astigmatism to read a chart while looking through lenses of different strengths on an optical refractor.
They will eventually find the lenses that correct your vision properly.
3. Keratometry
Keratometer or keratometry is an examination that aims to measure the curve or curvature of the cornea.
In addition, an ophthalmologist may also use corneal topography. The goal is to find out more information about the shape of the cornea’s surface.
4. Topography
This test aims to diagnose the potential for keratoconus. Later, the results of this test will determine what type of surgery will be performed if necessary.
Complications of Astigmatism
Complications that can be caused by astigmatism are amblyopia or also called lazy eyes, if astigmatism has been experienced in one eye since birth.
This happens because the brain is used to ignoring signals sent by the eyes.
Amblyopia is treatable if diagnosed and treated early before the visual pathways in the brain are fully developed.
In this way, the child will avoid amblyopia.
Astigmatism Treatment
In mild cases, astigmatism may not require treatment.
However, in severe astigmatism, the doctor will recommend several treatment methods, namely:
1. Use of Corrective Lenses
Corrective eyeglasses and contact lenses prescribed by a doctor are the most common and least invasive treatments for astigmatism.
2. Orthokeratology (Ortho-K)
Orthokeratology (Ortho-K) is an astigmatism treatment that uses rigid contact lenses to temporarily correct the irregular curvature of the cornea.
3. Operating Procedure
In severe cases of astigmatism, your doctor may also recommend refractive surgery.
This type of surgery involves using a laser or a small knife to reshape the cornea of a person with astigmatism and correct it permanently.
There are three common surgeries for astigmatism. Examples include laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and radial keratotomy (RK).
It is important to remember that all types of surgery carry a risk of side effects and complications.
Therefore, it is best to consult an eye doctor first before undergoing a surgical procedure for astigmatism.
Astigmatism Prevention
Astigmatism cannot actually be prevented. However, you can have regular eye checkups which are important for your vision and eye health.
Because astigmatism can increase slowly, early detection of this condition is very important.
Interestingly, regular eye examinations are also useful for detecting various other vision problems.