Astigmatism is a type of refractive error. Under normal circumstances, the degree of astigmatism is usually relatively stable and does not usually change much. If the astigmatism increases, it depends on these two conditions: first, a mild increase, such as a small increase in the magnitude of astigmatism with age, for example, within 100 degrees, is a physiological change. This occurs mainly because the shape of the cornea becomes further irregular with age. The second, mainly seen in cone corneal disease, is because cone corneal is a pathological change in the cornea, the shape of the cornea becomes more and more irregular with age, and it will form a conical shape, so it will lead to a very significant increase in the degree of astigmatism, and in serious cases it will cause corneal perforation.