What is astigmatism? Symptoms of astigmatism and how to prevent it

1. What is astigmatism?

Astigmatism is a refractive abnormality of the eye that is related to the curvature of the cornea. The human eye is not perfect, and if the cornea is curved at one angle and flatter at another, light rays cannot be accurately focused on the retina, a condition known as astigmatism. People with astigmatism have difficulty seeing things in detail. In general, astigmatism does not occur on its own, and the patient's eyes are usually accompanied by nearsightedness or farsightedness.

2. Causes of astigmatism

The so-called astigmatism refers to regular astigmatism, most of this kind of astigmatism is congenital, mainly caused by abnormal corneal curvature, in normal infants, the prevalence rate of this astigmatism is quite high, which may be related to the compression of the upper eyelids, sometimes called physiological astigmatism, the degree is very slight (25-50 degrees), this astigmatism may decrease slightly with age, and the change is not large.

Astigmatism caused by lenses is rare, some are acquired astigmatism, such as eyelid long needles or milidia, long-term eye posture (such as squinting, rubbing eyes, lying down to read, etc.), eyelids compressing the cornea, will also change the corneal curvature, increase the degree of astigmatism, in addition, eye surgery (such as cataract and corneal surgery), may also change the degree and axis of astigmatism.

Irregular astigmatism refers to the irregularity of the reflexion force of each meridian of the eyeball in the same meridian, mainly caused by corneal diseases The unevenness of the corneal surface, including keratitis, corneal ulcer, corneal scarring, keratoconus, etc., some cataracts are in the early stage, and the irregular reflexion force inside the lens can also be caused. Irregular astigmatism does not find two main meridians like regular astigmatism and cannot be corrected with cylindrical lenses.

3. Astigmatism symptoms

1. Ambiguity

Blurred vision is closely related to the degree and pattern of astigmatism.People with mild astigmatism usually have normal vision, but they may have headaches, eye strain, and blurred vision when looking at objects at a distance. People with severe astigmatism have blurred and distorted vision. It is not very clear to see far and near, and the working time of close range is slightly longer, that is, eye swelling, headache, reading, wandering or double vision.

2. Visual fatigue

Astigmatism, especially those with farsighted astigmatism, is prone to visual fatigue due to the need for constant fine adjustment of the blurred image on the retina, coupled with distorted vision. Young people with recurrent hyperopic astigmatism can often be compensated for by accommodation, which can form pseudosimple hyperopic astigmatism, pseudosimple myopic astigmatism or pseudorecurrent myopic astigmatism.

3. Normal head and eye position

In patients with high asymmetrical astigmatism in both eyes, in order to see more clearly, they often tilt their heads and cause strabismus, which can be restored after astigmatism correction. People with high astigmatism often squint when looking at distant targets, achieving pinholes and fissures to improve vision. Seeing through pinholes or fissures can reduce the impact of astigmatism on vision.

4. Astigmatism treatment

1. Mild regular astigmatism does not need to be corrected if there is no eye fatigue or blurred vision, on the contrary, if there is any of the above discomfort, although the degree is not high, it should also be corrected.

2. Patients with high astigmatism should be corrected with cylindrical scope, if they cannot adapt to all corrections, they can be given a lower degree first, and then gradually increase.

3. Irregular astigmatism cannot be corrected with a cylindrical lens, and contact lenses can be tried.

5. How to prevent astigmatism

1. When reading a book, the light should be sufficient, and the light should come from the left rear; Correct posture and a distance between 30 cm and 40 cm. Don't read in a rickety car, and don't read while lying down.

2. When choosing reading materials, the font should be clear and not too small.

3. The height of the TV is a little below the parallel line of the eyes, and it must be 5-7 times the diagonal of the TV screen to watch TV. Read a book for no more than one hour in a row, with a 5-minute break every 30 minutes. Nutrition should be balanced. Go to the countryside and see the green wilderness in the distance. If you need glasses, you should be examined by a doctor and then dispensed with glasses. Take the initiative to get in touch with the school and actively cooperate.