II. Types of Astigmatism

1. Corneal Astigmatism: This is the most common type, caused by a change in the curvature or shape of the cornea.

2. Lenticular Astigmatism: Occurs when there is a change in the lens of the eye.

3. Myopic Astigmatism: Commonly seen in people with myopia.

4. Hyperopic Astigmatism: Often occurs in patients with hyperopia.

5. Mixed Astigmatism: Characterized by one eye being hyperopic and the other being myopic.

III. Symptoms of Astigmatism

1. Reduced Vision: This is the most prominent symptom of astigmatism, which affects the ability to see both near and far objects. Blurred vision or other visual distortions are common.

2. Squint: When the eyes have difficulty seeing clearly, a common reaction is to partially close the eyelids together, resulting in a squint.

3. Eye Fatigue: Squinting due to unclear vision can lead to eye fatigue, causing a heavy feeling, tearing, or a burning sensation in the eyes. Headaches due to eye fatigue are also common.

4. Visual Impairment in the Dark: Astigmatism sometimes makes it difficult for the eyes to adapt to changes in light. That is, some people may experience impaired vision at night or in other low - light conditions.

IV. Causes of Astigmatism

V. Risk Factors of Astigmatism

1. Family History of Astigmatism: Genetic factors may play a certain role in the development of astigmatism.

2. Eye Injury: External force impact or other damage to the eye may cause astigmatism.

3. Undergoing Eye Surgery or Complications after Surgery: Eye surgery may change the structure or physiological state of the eye, leading to astigmatism.

VI. Diagnosis of Astigmatism

1. Visual Acuity Test: By reading letters of different sizes on a chart to test the ability to see near and far objects.

2. Refraction Test: To assess the degree of refractive error of the eye (i.e., the inability of the eye to focus accurately).

3. Retinoscopy: Using a handheld device called a retinoscope to test the refractive error of the eye.

4. Corneal Curvature Measurement: Using a keratometer to measure the curvature and shape of the cornea.

5. Corneal Thickness Measurement: Using a pachymeter to measure the thickness of the cornea to determine whether eye surgery is suitable.

VII. Treatment of Astigmatism

1. Mild Astigmatism: Mild cases of astigmatism may not necessarily require immediate treatment, but usually need regular follow - up examinations to monitor the development of the condition.

2. Severe Astigmatism: More severe cases of astigmatism may require treatment measures such as wearing glasses, using corrective lenses, or having surgery.

• Astigmatic Keratotomy: By making tiny incisions on the cornea to change the path of light entering the eye.

• Laser - Assisted in Situ Keratomileusis (LASIK): Relying on a laser beam to remove the inner corneal tissue and reshape the eye.

• Photorefractive Keratectomy (PRK): Similar to LASIK, using a laser to ablate the inner and outer layers of the cornea to change the shape of the eye.

• Refractive Surgery: If the ophthalmologist determines that surgery is appropriate, some surgical methods that help reshape the cornea to correct astigmatism may be recommended. These surgeries usually have a relatively high success rate and can bring relatively long - lasting effects. Common surgical types include:

• Orthokeratology: Also known as overnight contact lens wear, it is a non - surgical treatment method. Patients wear special hard contact lenses at night to help adjust the shape of the cornea. During this process, as the eye structure gradually changes, one or more pairs of overnight contact lenses may be needed. It should be noted that this change is not permanent, but continuous treatment can help improve vision.

• Glasses and Contact Lenses: Some patients may need to wear glasses made of special lenses (cylindrical lenses) to relieve astigmatism symptoms. Cylindrical lenses can improve visual acuity (clarity) and reduce eye fatigue associated with astigmatism. If a patient prefers contact lenses to glasses, they can consult an ophthalmologist to see if astigmatic contact lenses are suitable. It should be remembered that people who wear contact lenses must pay extra attention to cleaning and caring for the lenses to prevent infection or other eye problems. At the same time, most ordinary soft contact lenses have no significant improvement effect on astigmatism because they are designed for round corneas, while the corneas of people with astigmatism are more curved, like a rugby ball. People with astigmatism can benefit from wearing "astigmatic" contact lenses. These lenses have a specific shape that can effectively reduce the impact of astigmatism and improve symptoms. The contact lenses of astigmatic lenses also have lines or marks specifically used to correct astigmatism. The purpose of these lines is to help the doctor check whether the lenses fit properly and are worn correctly on the eyes.

VIII. Prevention of Astigmatism

IX. Related Complications of Astigmatism

1. Vision Loss: Myopia (inability to see clearly in the distance) and hyperopia (inability to see clearly nearby objects) often occur along with astigmatism.

2. Cataracts: Cataracts are cloudy spots on the lens that form with age. Research has found that 35% - 40% of cataract patients also have astigmatism.

3. Amblyopia: Also known as lazy eye, it is a visual defect in one eye caused by overuse or dependence on the other eye. Monocular astigmatism in infancy or childhood may lead to this disease.

4. Strabismus: Strabismus, commonly known as "cross - eyed", refers to the inability of the eyes to align properly. Some studies have shown that untreated astigmatism sometimes increases the risk of developing this disease.

X. Frequently Asked Questions about Astigmatism

1. Can a person with astigmatism have 20/20 vision?
   Generally, without correction, it is difficult for a person with astigmatism to achieve 20/20 standard vision. However, through appropriate corrective means such as wearing glasses or contact lenses, some patients can restore better vision levels.

2. What will happen if astigmatism is not treated?
   If astigmatism is not treated, symptoms such as blurry vision and visual distortion will persist and may gradually worsen, seriously affecting daily life, such as reading, driving, work, etc. It may also increase the risk of developing other vision problems such as amblyopia and strabismus.

3. Do people with astigmatism need to wear glasses?
   Not all people with astigmatism must wear glasses. Mild astigmatism may not require correction, while moderate to severe astigmatism patients usually need to wear glasses or contact lenses for vision correction. The specific decision depends on various factors such as personal vision status, the degree of astigmatism, and lifestyle needs, and is comprehensively judged by the ophthalmologist.