Astigmatism is a condition in which parallel light from a distance enters the eye in an unadjusted state and, after passing through the refractive system, does not focus as a dot on the retina, but forms a focal line. Astigmatism is usually not significantly affected when looking at lights at night if the degree is relatively low. In contrast, medium and high astigmatism, especially mixed astigmatism, has a dilated pupil at night, so the effect on vision will be more obvious. Patients will feel that in addition to not seeing far clearly, the light will change from a point light source to a line light source, and even form a virtual shadow next to it, and patients feel that there are double shadows appearing, and after a long time patients have eye pain and headache, especially the frontal pain is more obvious before, and the symptoms of visual fatigue are especially easy to appear.