What is astigmatism?

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What is astigmatism?

The refractive power of the eyeball on each meridian is uneven. After the parallel light enters the inside of the eyeball, due to the different refractive power of the eyeball on each meridian, it cannot gather at a point (focus) on the retina, but form some scattered focal points.

A normal eye shows light rays converging precisely on the retina, while an eye with astigmatism shows light rays focusing at a different point, resulting in a blurred image on the retina.

Astigmatism Cause Analysis

The visual effects of astigmatism patients were found through optometry. From an optical point of view, eye astigmatism means that when parallel rays of light from the outside enter our eyes, one image cannot be produced, and two or more images will be formed.

The status of astigmatic eyes and normal eyes during visual acuity exam

Astigmatism cannot form a clear image with the help of accommodation or moving the distance between the target and the eye, so the lines look blurry.


Astigmatism can be roughly divided into:

1. Regular astigmatism, irregular astigmatism;

2. Astigmatism along the rule, against the rule astigmatism, oblique axis astigmatism;

3. Simple myopia astigmatism, simple hyperopia astigmatism, compound myopia astigmatism, compound hyperopia astigmatism, mixed astigmatism;

4. Corneal astigmatism, crystal astigmatism, etc.


What are the hazards of astigmatism?

1. Visual fatigue

Due to the different refractive power of each meridian, astigmatism cannot form a focal point for parallel light refraction, but two focal lines. Such imaging is easy to induce instability in adjustment, sometimes clear, sometimes blurred, and easy to visual fatigue.

2. The vision loss

Astigmatism, the color of the optotype in the direction of the focal line away from the retina becomes lighter, the edge is blurred, it is not easy to identify, the visual acuity decreases, and in severe cases, diplopia occurs.

3. Blurred vision

Patients often have the habit of squinting the eyelids halfway into a gap in an attempt to make objects more clearly seen.

4. Abnormal head position and eye position

People with a high degree of asymmetrical astigmatism in both eyes, in order to see more clearly, often adopt a tilted head position, which leads to strabismus.

5. Often squinting

In order to see distant objects clearly, patients with high astigmatism often like to squint, frown, or stretch their eyelids by themselves to achieve the effect of pinhole lenses and slit lenses to improve vision.


To protect your eyes, experts recommend:

1. It is best to do regular eye examinations, 1 or 2 times a year. Develop good hygiene habits and do not touch your eyes with hands or other objects to avoid contagion of eye diseases.

2. The reading posture should be correct, and keep a distance between 30 cm and 40 cm. When choosing reading materials, the font should be clear and not too small.

3. Do not rub your eyes, protect your eyes, and avoid eye trauma is the way to prevent pathological astigmatism.

4. Astigmatism is mainly determined by genes, just like appearance and height are determined by genes. Astigmatism is a type of refractive error that is very common, not a "disease".

5. For patients with astigmatism, they should wear prescription glasses in time, so that the appropriate degree will reduce the symptoms of astigmatism and avoid the symptoms of eye fatigue during work and study.

Depicting a night driving scene, eyes with astigmatism see light streaks extending from traffic lights and car taillights, while eyes with normal vision see clear lights without streaks.

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