Astigmatism of the eye is a type of refractive error caused by an uneven curvature of the cornea's surface, resulting in different refractive powers along different axes. Once astigmatism occurs, particularly with a high degree of astigmatism, there can be a noticeable decrease in vision, distortion in sight, or in severe cases, significant eye fatigue. However, it generally does not lead to pupil dilation. Pupil dilation is caused by the paralysis of the ciliary muscle due to internal and external factors, resulting in enlarged pupils. Therefore, if symptoms of astigmatism appear, it is advisable to visit a hospital promptly for accurate diagnosis and appropriate treatment.