It seems that there are very few people who are only nearsighted. Why do many nearsighted people have astigmatism more or less?
First, the relationship between astigmatism and myopia
Medically speaking, myopia and astigmatism are both manifestations of ametropia. In fact, it is very simple to distinguish myopia from astigmatism. Myopia is clearer when it is near, but not when it is far away. Astigmatism means that the edge of the object is blurred, and severe astigmatism may even cause ghosting, which is difficult to see regardless of the distance.
Astigmatism itself can develop into myopia, and astigmatism combined with myopia can promote the occurrence and development of myopia.
Second, what kind of experience is eye astigmatism?
People with astigmatism will have symptoms such as decreased vision, distorted vision, diplopia in one eye, poor vision at night (different from night blindness), head and neck tilt when seeing things, habitual squinting, fatigue and so on. When checking the companion e sign in the eye chart, one direction can be identified, but the vertical direction cannot be identified, and the visual performance is uneven.
For patients with high astigmatism, only mild or rare symptoms such as blurred vision, headache or visual fatigue often appear, but when high astigmatism is nearly completely corrected, these symptoms may appear instead, which is caused by the remaining uncorrected mild astigmatism.
In addition, they often have to squint their eyes to reduce the blur of the object image and move the object closer to get a larger retinal image.
Third, the causes of astigmatism deepening
The emergence of astigmatism is related to congenital factors and acquired factors: congenital astigmatism refers to the problem that some children will have astigmatism during embryonic development, and it is not clear what causes it in medicine at present. Therefore, if it is congenital, it is difficult to prevent it.
Except congenital astigmatism, the appearance and development of other astigmatism types are almost inseparable from two points: narrowing eyes and rubbing eyes. This is because acquired astigmatism is mostly caused by uneven cornea, which may be caused by frequent eye rubbing and strabismus.
Although there is no clinical experiment to prove that rubbing eyes and squinting will definitely cause astigmatism, it is related to some extent. Another point is that some nearsighted friends don't like to wear glasses. They are worried that wearing nearsighted glasses will get deeper and deeper and they will never get rid of it. So once they are blurred, it is easy to form the habit of squinting. In fact, this will accelerate the development of myopia and also lead to the deepening of astigmatism.
Please pay attention! ! !
If the astigmatism changes from 100 degrees to 200 degrees, 300 degrees, or even higher, we should be careful of a special corneal disease-keratoconus, which will lead to blindness, and we must review the corneal topography regularly.
Fourth, can astigmatism be saved?
Not all astigmatism needs to be corrected by glasses, and patients with astigmatism should pass medical optometry.
Astigmatism is mainly corrected by glasses, including frame astigmatism lens correction and contact lens correction. If you are an adult, you can consider laser surgical correction. Laser surgery can correct not only myopia, but also astigmatism. Cataract patients can correct astigmatism by implanting an intraocular lens with astigmatism correction function.
Conclusion: Astigmatism below 50 degrees is mostly physiological astigmatism, which has little effect on vision. But astigmatism should be corrected as soon as possible, otherwise the development of visual function will be inhibited to some extent. The older you get, the worse the correction effect will be. Early correction can not only promote the development of visual function, but also reduce the wrong reaction of object deformation and spatial positioning. But the specific treatment should be based on the doctor's advice.