What is Astigmatism, Its Causes, Symptoms, and Treatment

Astigmatism is a common vision problem caused by irregularities in the shape of the cornea. As a result of this condition, symptoms such as difficulty seeing at night or blurred vision may occur. In astigmatism, the eye's lens or cornea has an irregular curvature. This irregular curvature of the cornea or lens can lead to light being refracted incorrectly on the retina or cause changes in the range of refraction. Astigmatism can occur alongside hyperopia (a vision problem in near sight) or myopia (a vision problem in far sight). To correct astigmatism, an eye doctor may prescribe glasses or contact lenses. Additionally, surgical methods may also be used for treatment.

What is Astigmatism?

Ideally, the eyeball is shaped like a round ball. In this case, light entering the eye is evenly bent, allowing for a clear image to form. However, when the cornea loses its ideal round shape, light entering the eye bends more in one direction. This uneven bending of light means that only part of the objects is in focus. As a result, distant objects may appear blurry and wavy.

Astigmatism is a medical term that refers to the eye shape being more curved than normal. This condition causes light entering the eye to bend unevenly, affecting vision regardless of distance.

Astigmatism can arise due to a problem with the cornea or lens. If there is a defect or distortion in the cornea, corneal astigmatism occurs. When there is a distortion in the lens, lenticular astigmatism develops.

What are the Symptoms of Astigmatism?

The symptoms resulting from astigmatism can vary from individual to individual. Blurred vision is the most commonly seen symptom of astigmatism. Other symptoms associated with astigmatism may include:

• Difficulty seeing at night
• Pain, burning, or discomfort in the eye
• Headaches
• The need to squint
• Double vision

These types of symptoms can arise from astigmatism or other vision problems. If one or more of these symptoms occur, it is important to consult a healthcare facility for early diagnosis and treatment of any underlying causes.

What Causes Astigmatism?

The exact cause of astigmatism is not yet clearly understood. It may also result from the eyelids exerting too much pressure on the cornea. Additionally, genetic factors play a significant role in the development of astigmatism. This condition can be inherited at birth or develop during other stages of growth after birth.

Vision problems, such as blurred vision, can also occur as a result of an injury to the eye or following eye surgery. Moreover, a rare condition known as keratoconus can lead to astigmatism. This eye defect affects the cornea, causing the layer over the cornea to thin and protrude. As a result of these changes in the cornea, sensitivity to cloudy or bright light and clear weather may occur.

What Are the Degrees of Astigmatism?

Astigmatism is a common type of refractive error. The effect of this refractive disorder on visual quality is determined by the astigmatism severity scale. The severity scale of astigmatism ranges from mild (less than 1.00 diopter) to severe (more than 3.00 diopters). Astigmatism degrees can be classified as follows:

• Mild Astigmatism: Values of 1.00 diopter or lower are considered mild astigmatism or normal. In this case, there may be no symptoms in the body. Corrective lenses or eye surgery are not needed for clear vision in mild astigmatism.
• Moderate Astigmatism: Values between 1.00 and 2.00 diopters are referred to as moderate astigmatism. Moderate astigmatism is more serious than mild astigmatism. In this case, corrective lenses or laser eye surgery are usually required to achieve clear vision. Glasses and contact lenses can improve vision problems associated with moderate astigmatism.
• Severe Astigmatism: Severe astigmatism refers to values between 2.00 and 3.00 diopters and can cause serious symptoms that affect daily functioning. Blurred vision caused by severe astigmatism can lead to headaches that impact overall health.
• Extreme Astigmatism: Values of 3.00 diopters or higher are considered extreme astigmatism. In cases of extreme astigmatism, treatment is necessary to see objects both near and far.

Who is Affected by Astigmatism?

Astigmatism can occur in individuals of various ages, from infancy to adulthood. Different risk factors may contribute to the development of astigmatism. Some of these risk factors include:

• A family history of astigmatism or other eye diseases, such as keratoconus (degeneration of the cornea)
• Conditions that cause damage to the cornea
• Certain vision defects, such as myopia or hyperopia
• A history of specific eye surgeries, such as cataract surgery (surgical removal of the eye lens)

Individuals with these types of conditions may develop astigmatism.

How is Astigmatism Diagnosed?

Astigmatism can be easily diagnosed through an examination by an eye doctor. The symptoms present in the individual are assessed by the doctor to diagnose astigmatism. Based on these symptoms, various tests may be conducted to evaluate the presence of astigmatism. Some of the tests used in the diagnosis of astigmatism include:

• Visual Acuity Test: This test assesses normal visual ability. It involves identifying symbols or letters on a wall chart during an eye examination.
• Refraction Test: This test evaluates how the eye bends light and focuses it.
• Slit Lamp Examination: The slit lamp is conducted using a special microscope with bright light. This microscope adjusts the brightness and thickness of the light beam to visualize different layers and parts of the eye, allowing for the investigation of astigmatism issues.
• Keratometer: This machine measures the curvature of the cornea, providing information about its shape and how well it can focus.
• Corneal Topographer: This technology provides detailed information about the shape of the cornea. During the test, the individual is asked to look at a specific point, while the device collects thousands of small measurements. A colored map of the cornea is generated from the data obtained via a computer.

Astigmatism Treatment

In the treatment of astigmatism, different methods can be applied depending on the degree of astigmatism and individual characteristics. Symptoms arising from non-severe astigmatism can be improved with the use of glasses or contact lenses. The lenses used in treatment are curved to counteract the shape of the cornea or lens that causes blurred vision.

In cases of more severe astigmatism, rigid gas-permeable contact lenses may be preferred. In this treatment, lenses worn while sleeping help reshape the cornea. To maintain the new shape formed in the cornea, lens use must continue at specific intervals.

In some cases of severe astigmatism, surgical procedures may be used for treatment. This procedure, known as laser eye surgery (LASIK or PRK), reshapes the cornea to allow the eye to focus light better. The eye is numbed using drops applied during the procedure. After anesthesia, the doctor uses a sterile mechanical device to create a thin flap in the cornea. The cornea is pulled back to expose its central layers. Then, a laser is used to reshape the cornea, and it is returned to its original position.

Astigmatism is a visual defect caused by a mismatch in the curvature of the eye's cornea or lens. This condition can manifest with symptoms such as blurred vision, double vision, eye strain, headaches, and difficulty seeing at night. Astigmatism often occurs congenitally and may be seen alongside myopia or hyperopia. Regular doctor check-ups are crucial for effectively treating this condition. Attending doctor appointments at regular intervals can help in the early diagnosis and treatment of astigmatism, thereby preventing its progression.