Astigmatism is a type of refractive error. Astigmatism is a kind of refractive error, mainly due to corneal irregularities, according to the different causes, generally divided into two kinds, the first is physiological astigmatism, refers to the congenital development of the cornea is not caused by, this condition is generally seen in children and adolescents, and the degree is not too big, rarely more than 600 degrees, generally with the growth of age, the degree usually does not change, even with glasses This condition is usually seen in children and adolescents. There is another kind of acquired astigmatism, mainly secondary to corneal disease, such as cone cornea, corneal scar, corneal ulcer, etc., is due to external factors that cause irregularities in the shape of the cornea, with the aggravation of the disease or age, the prescription may become larger and larger, in this case, you need to go to the hospital to do the relevant examination, early intervention to avoid further deepening of the prescription.