Why is there astigmatism

Nowadays, due to the popularity of electronic products, there are more and more people who are addicted to their phones. The impact of electronic radiation on people's eyes is becoming more and more obvious, and more and more cases of myopia are occurring. But in addition to the problem of myopia, many other eye diseases begin to occur, astigmatism is one of them, which will directly cause people to be unable to focus when observing things. So let us discuss together today the reasons why astigmatism occurs.

We often hear that someone has astigmatism. Why does astigmatism occur? There are many reasons for this, the most important of which is caused by changes in the curvature of the cornea of ​​the eye. The cornea, also called the "black pupil", is a window in front of the eyeball. It is not only smooth and transparent, but also in a complete hemispherical shape. Its main function is to pass light, concentrate it, make it enter the pupil and reach the retina at the fundus, form a focus, and then reflect it to the brain, so that people can clearly see the outside world. Therefore, when the curvature of the hemispherical cornea changes, like an unevenly polished lens, and the surface becomes uneven and irregular, the external light cannot form a focus on the retina, but diffuses in all directions, making the brain's perception of external objects blurred, thus producing astigmatism. This type of astigmatism is medically called irregular astigmatism. Because the curvature of the cornea changes so much, it is difficult to correct with glasses.

There is also a type of astigmatism called regular astigmatism, which is caused when the curvature of the cornea in a certain direction is inconsistent with its vertical direction. There are many types of astigmatism, including simple hyperopic astigmatism, simple myopic astigmatism, compound hyperopic astigmatism, compound myopic astigmatism and mixed astigmatism, etc. Most of them are caused by different refractive powers of the cornea and exist at the same time as myopia or hyperopia, and can be corrected with glasses.

There are two reasons for irregular astigmatism caused by uneven cornea and incorrect curvature: one is congenital and inherited, and the other is due to acquired corneal disease. If the cornea is ulcerated or injured, scars will form after healing, which will cause the cornea to be uneven and have an irregular curvature.

Regular mild astigmatism generally does not affect vision, but may cause discomfort such as eye fatigue. Many people will experience headaches, soreness in the eyes and around the eye sockets and other discomforts when using their eyes for a long time. A few people even have symptoms of nausea and vomiting, which has a certain impact on their health and work. When the astigmatism is more serious, objects appear blurry, which has a greater impact on work.