Astigmatism is a condition in which parallel light rays are refracted by the refractive system of the eye and do not converge into a single point, but spread out into many light images, hence the name astigmatism. Why is the focal point scattered? It is because the eye is not round enough. This is due to the uneven density or uneven surface of the retina, crystalloid, and cornea. Therefore, most people’s eyeballs are not [just] that round. No astigmatism at all? Usually it’s just a minor difference. According to research, astigmatism is often aggravated by poor eye posture. For example, lying down and reading, or even squinting or squinting can cause improper pressure on the eyelids and affect their normal development, so eliminating bad habits is the way to prevent astigmatism and myopia. These habits are also often the cause of myopia, so some people think that myopia causes astigmatism, but in fact the two are not related. The prevalence of this kind of astigmatism is quite high in normal infants, and may be related to the pressure of the upper eyelid, sometimes called physiological astigmatism, the degree is very slight, this kind of astigmatism may be slightly reduced with the increase of age, once the change is not large. Irregular astigmatism refers to the unevenness of the corneal surface caused by corneal diseases, including keratitis, corneal ulcers, corneal scarring, cone corneas, etc. Some cataracts are also caused by the irregularity of the refractive power inside the crystalloid in the early stages. In terms of examination, preschool children with more than 200 degrees of astigmatism will have a partly clear and partly blurred image and have the habit of squinting with their head tilted. Parents should take their children to the eye examinations as early as possible to avoid missing the golden period of treatment (before 6 years old), resulting in amblyopia. Regular vision checkups, early detection of vision abnormalities, and early treatment will prevent parents and children from having a lifetime of regrets.