What is astigmatism? Learn about astigmatism

Astigmatism is an English word that when translated into Vietnamese is astigmatism. A common eye disease. Astigmatism is a common and often treatable defect in the curvature of the eye that causes blurred near and far vision.

Astigmatism occurs when the front of the eye (cornea) or the lens inside the eye has mismatched curves. Instead of having a curve like a round ball, the surface is egg-shaped. This causes blurred vision at all distances.

Astigmatism is usually present at birth and can occur in combination with nearsightedness or farsightedness. Often it is not pronounced enough to require corrective action. Once there, the treatment options are corrective contact lenses or surgery.

Symptoms of Astigmatism

Signs and symptoms of Astigmatism may include:

• Blurred or distorted vision
• Eye fatigue or discomfort
• Headache
• Difficulty with night vision
• squint

When to see a doctor?

See an ophthalmologist if eye symptoms cause you to lose interest in activities or interfere with your ability to perform daily tasks. Your ophthalmologist can determine if you have astigmatism and, if so, to what extent. He or she can then advise you on options for correcting your vision.

Children and adolescents

Children may not realize their vision is blurry, so they need to be screened for eye disease and have them checked by a pediatrician, optometrist, optometrist, or other trained screener. Vision tests at the following ages and time periods.

• During the neonatal period
• At children’s health visits until they reach school age
• During school years, every 1 to 2 years during a child’s physical exam, at an optometrist, or through school or public screenings

Causes of Astigmatism

The eye has two structures with curved surfaces that bend (refract) light onto the retina, creating images:

• The cornea, the transparent surface of the eye along with the tear film
• The lens, a clear structure inside the eye that can change shape to help the eye focus on nearby objects

In a perfectly shaped eye, each of these elements has a rounded curvature, like the surface of a smooth ball. The cornea or lens with such curvature bends (refracts) all incident light equally to produce a sharp focused image directly on the retina at the back of the eye.

Refractive error

If the cornea or lens is egg-shaped with two mismatched curves, the light rays are not bent the same, which means two different images will form. These two images overlap or combine and lead to blurred vision. Astigmatism is a type of refractive error.

Astigmatism occurs when the cornea or lens curves more in one direction than in the other. You have corneal astigmatism if your cornea has mismatched curves. You have lenticular astigmatism if your lenses have mismatched curves.

Either type of astigmatism can cause blurred vision. Blurry may occur more in one direction: horizontal, vertical, or diagonal.

Astigmatism can be present at birth or can develop after injury, disease, or eye surgery. Astigmatism does not cause or worsens when reading in poor light, sitting too close to the television, or squinting.

Other refractive errors

Astigmatism can occur in combination with other refractive errors, including:

• Myopia (nearsightedness). This happens when the cornea is too curved or the eye is longer than normal. Instead of being focused precisely on the retina, light is focused in front of the retina, making distant objects appear blurred.
• Farsightedness (farsightedness). This happens when the cornea is too curved or the eye is shorter than normal. The opposite effect of myopia. When the eye is in a relaxed state, light never converges at the back of the eye, making nearby objects appear blurry.